Laboratory tests have found no traces of anthrax in an apartment in Crown Heights, Brooklyn, where a man worked on unprocessed animal hides obtained from Vado Diomande, the New York City man who contracted inhalation anthrax this month.

The city's Department of Health and Mental Hygiene, which released the test results yesterday, said it had told three people who lived in the apartment, including Mr. Diomande's associate, that they could immediately discontinue the antibiotics they had been taking.

Four other people who worked with Mr. Diomande and may have had contact with animal skins continued to take antibiotics, although none have exhibited any symptoms of infection.

The negative test results and the reduction in the number of people on antibiotics were among the most promising developments in the case since Wednesday, when federal authorities confirmed that Mr. Diomande had contracted inhalation anthrax in the first naturally occurring case in the United States since 1976. A musician and a dancer, Mr. Diomande, 44, is thought to have inhaled anthrax spores while handling untreated animal skins, which he stretched and scraped to make drums.

Mr. Diomande, who collapsed on Feb. 16 after a performance in Mansfield, Pa., remained in serious condition yesterday at Robert Packer Hospital in Sayre, Pa.

This week, the federal Environmental Protection Agency will begin cleaning Mr. Diomande's fifth-floor apartment at 31 Downing Street in Greenwich Village and his sixth-floor studio in a warehouse at 2 Prince Street near the Brooklyn waterfront, officials said yesterday.

On Friday, lab tests detected the presence of anthrax spores in both places, as well as in a Dodge van that Mr. Diomande is believed to have used to transport the skins.

The agency will clean the hallways and other common areas of the apartment building and will clean other residents' apartments if they ask for it. The extent of the cleanup of the Brooklyn warehouse is still being determined, officials said, as is what will be done to the van.

"Our agency has responded to anthrax incidents in the past and has a great deal of expertise in this area," said Alan J. Steinberg, a regional administrator for the Environmental Protection Agency, which handled the cleaning of several Congressional offices and a mail-distribution center in Washington after anthrax terrorism attacks in 2001.

A study published in Annals of Internal Medicine on Tuesday, the day before Mr. Diomande's case was disclosed, reviewed 82 inhalation anthrax cases worldwide, 70 of them fatal, from 1900 to 2001.

"Of the 12 patients who survived, they were much more likely to have received either multidrug antibiotic regimens or antiserum, to have had fluid drained from around their lungs, and to have received therapy in the early rather than later stages of the disease," said Dr. Jon-Erik C. Holty, the lead author of the study and a postdoctoral fellow in pulmonary and critical care medicine at Stanford University School of Medicine.

Mr. Diomande had chills, fever and fluid in his lungs when he collapsed, but after a week of hospitalization he was in stable condition. On Friday, his condition was changed to serious.

As government workers prepared to decontaminate the apartment of a man who contracted anthrax, tenants of the warehouse where he kept unprocessed animal skins complained yesterday that the closing of the building had hurt their livelihoods.

Lincoln Mayne, 34, an Australian fashion designer who pays $850 a month to rent a 500-square-foot studio in the eight-story building, at 2 Prince Street near the Manhattan Bridge in Brooklyn, said that his five employees had not been paid in a week and that two of them were planning to quit.

"It affects the momentum of my business," said Mr. Mayne, who said he had 2,000 T-shirts in the studio, worth $2,200, that were supposed to be shipped on Friday.

The anthrax patient, Vado Diomande, 44, remained in serious condition yesterday at Robert Packer Hospital in Sayre, Pa., although doctors there said that he had shown improvement. Officials believe he contracted inhalation anthrax, the first naturally occurring case of the disease in the United States since 1976, after working with unprocessed animal skins to make drums.

Last Friday, laboratory tests confirmed the presence of anthrax spores in Mr. Diomande's apartment in Greenwich Village, his work studio in the Brooklyn warehouse and in a Dodge van he is thought to have used to transport the skins. Officials have struggled with how to decontaminate the two buildings.

Mr. Diomande's fifth-floor apartment remains sealed, but other residents of the building, at 31 Downing Street, have been allowed to come and go. Starting tomorrow, workers for the federal Environmental Protection Agency will use a bleach solution and a high-efficiency particulate air-filter vacuum to clean the apartment and the building's common areas, including hallways.

Several of Mr. Diomande's possessions may have to be destroyed, but his family will be consulted before any such decision is made, said Mary Mears, a regional spokeswoman for the agency. The work is to be completed by Friday.

The fate of the warehouse is less certain. The building is mostly occupied by a self-storage company, but about 30 loft studios on the third and sixth floors have been rented, mostly to artists and musicians. (Mr. Diomande's studio is on the sixth floor.)

Mehatem Ashenaffi, 31, who runs an online bookstore with his partner out of a 1,000-square-foot studio that costs $1,400 a month in rent, said his business had been crippled. "If the doors aren't open, we can't sell," he said.

Thomas S. Beale, 27, a sculptor who pays $860 a month to rent a 600-square-foot studio, said he had asked government representatives when he could return, to no avail. "I've had one client who wanted to see my work, but he is leaving the country on Tuesday," Mr. Beale said. "I was told it would be 7 to 10 days before we could go back in. It's an incredible frustration and inconvenience."

Mr. Mayne, Mr. Ashenaffi and Mr. Beale, who work on the third floor, met last night with Mr. Ashenaffi's business partner and two other tenants.

Erik T. Ekstein, one of three owners who hold the lease on the building, said they had hired a contractor to do the cleanup and were awaiting approval by the city's Department of Health and Mental Hygiene and by the Environmental Protection Agency, which will oversee the work.

"We definitely feel for our tenants," he said in a telephone interview. "We will do everything in our power to get them back into the building as quickly as possible."

He said he hoped the plans would be approved by tomorrow. The environmental agency has scheduled a meeting with the tenants tomorrow night.

John Holl contributed reporting for this article.

Environmental cleanup workers entered two New York City buildings yesterday where anthrax spores were detected last Friday and began a painstaking decontamination process under close monitoring from federal and city officials.

At 9 a.m., workers hired by the federal Environmental Protection Agency started cleaning the hallways and the fifth-floor apartment of Vado Diomande, the musician who contracted inhalation anthrax last month. The presence of anthrax in his building, at 31 Downing Street in Greenwich Village, was confirmed last Friday, but residents have been allowed to come and go. The work was completed about 9 p.m.

More complicated is the cleanup of the Brooklyn warehouse where Mr. Diomande is believed to have inhaled anthrax spores from working with unprocessed animal hides that he used to make drums. That cleanup, which began around noon yesterday, is expected to take three to five days.

Since Feb. 22, when Mr. Diomande's diagnosis was confirmed, none of the 30 commercial tenants have been allowed to enter the eight-story building, at 2 Prince Street near the foot of the Manhattan Bridge in Brooklyn.

Mr. Diomande remained in serious condition yesterday at a hospital in Pennsylvania, although Dr. Melanie A. MacLennan, a physician and a friend of Mr. Diomande's, said that his wife, Lisa, had told her that his vital signs had improved.

Last night, at a 90-minute meeting at the MetroTech Center in Downtown Brooklyn, tenants of the warehouse listened to presentations from the city's Department of Health and Mental Hygiene and Department of Small Business Services, and from the E.P.A. Jessica Leighton, the city's deputy commissioner for environmental health, said the cleanup workers were being extremely cautious even though the risk of infection was "virtually nil."

The officials explained the cleanup process. Workers in hazardous-materials suits are passing high-efficiency particulate air-filter vacuum machines over floors, and soaking hard surfaces with a bleach solution and rinsing them off, usually after an hour, with soap and water. Workers are also collecting air and dust samples in petri dishes and waiting to see if spores develop after 24 to 48 hours. Some materials that cannot be cleaned, like certain carpets, will be double-wrapped in plastic, sprayed with bleach, boxed, sprayed and then incinerated.

The tenants, who had complained that their livelihoods were hurt, left the meeting with mixed reactions. "We're being told that it's safe, yet we still cannot get in for another three, five or seven days," said Peter D. Gerakaris, 25, an artist who occupies a third-floor studio.

"Three days ago, we didn't know what was going on," said Lincoln Mayne, 34, a fashion designer who rents a third-floor studio. "Now I feel there's a face to the process."

Bill Holcomb, 31, who runs a recording studio across the hall from Mr. Diomande's space on the sixth floor, said he would not be willing to return until he was assured that air vents and entryways had tested negative for anthrax. "If I can get that on paper, I can continue to conduct business with peace of mind," he said during the meeting.

Erik T. Ekstein, one of the three owners who hold the lease on the warehouse, hired Trade-Winds Environmental Restoration, which focuses on hazardous-waste removal, to do the work.

The warehouse was the site of another environmental controversy only a few years ago. In 2002, the building's owner, Marvin Rubenstein, and his son Isaac were convicted in Federal District Court in Brooklyn of violating the Clean Air Act by failing to follow work standards when they had workers remove asbestos from the building in 2000. The two men were sentenced to prison in 2003, but after an appeal, their sentences were reduced last year to time served.

A drummer from Manhattan who contracted inhalation anthrax last month after working with unprocessed animal skins suffered a "temporary setback" on Thursday evening, and was downgraded to serious condition, hospital officials said yesterday in a statement.

The drummer, Vado Diomande, 44, had been in fair condition at Robert Packer Hospital in Sayre, Pa. When reached by telephone yesterday, a hospital spokeswoman declined to elaborate on Mr. Diomande's condition or what problems he was having.

In a separate statement, Mr. Diomande's brother-in-law, Alexander Harman, said: "I know he is strong and can overcome all obstacles. He will thrive with the support of all who know him, and all who have newly come to know of him."

Mr. Diomande, founder of the Kotchegna Dance Company, collapsed on Feb. 16 after a performance in Mansfield, Pa.

Meanwhile, Mary Mears, a spokeswoman for the federal Environmental Protection Agency, said workers had finished recleaning Mr. Diomande's apartment at 31 Downing Street in Greenwich Village and had found no further traces of anthrax.

She said that workers were continuing the cleanup of two floors at a Brooklyn warehouse where Mr. Diomande worked with the skins, and that the results of tests determining if those floors could be reopened would be available early next week.

SAYRE, Pa., March 22 — Walking slowly but sporting a wide smile, Vado Diomande, the African dancer and drummer who contracted inhalation anthrax last month, entered a hospital auditorium here yesterday and spoke publicly for the first time since he fell ill. He thanked the doctors who have been treating him, talked about his plans for life after the hospital, and even did a quick dance.

"They do very good job," he said in halting English. "Because if not them, maybe I'm not here today."

Then, saying, "Just one step," he jumped into the air and did a quick dance to the applause of his family and the hospital's staff members.

Mr. Diomande, 44, a native of Ivory Coast in West Africa who lives in Greenwich Village with his wife, contracted the first naturally occurring case of inhalation anthrax in the United States since 1976. Health officials have said he fell ill after working with unprocessed animal skins to make drums.

Mr. Diomande said on Wednesday, however, that he had been working with a cowhide he purchased in New York about a week before he fell ill. While cutting the hide to make a bass drum, Mr. Diomande said, he noticed "powder" fall from the skin to the floor. Within a few days, he said, he was having trouble breathing and felt fatigued.

Initially, he told investigators that he had been working with a goatskin. In an effort to explain the discrepancy, Mr. Diomande's wife, Lisa, said he had spoken with investigators "through a great deal of pain, lack of breathing and drugs."

Mr. Diomande has spent more than four weeks in the hospital, and though he has lost 45 pounds, his condition has steadily improved. He was released late Wednesday evening.

He collapsed on Feb. 16 after a performance in Mansfield, Pa., and was taken to Robert Packer Hospital in Sayre, where he remained in intensive care.

"It was very painful," Mr. Diomande said of the night of his collapse. "After the show, to go upstairs, I could not walk. When I do, I walk five steps and have to rest. It was this sickness."

Doctors treated Mr. Diomande with antibiotics including Cipro, but said he had been placed on a ventilator for several weeks and had undergone operations to remove fluid near his lungs.

On Monday, his condition was upgraded from fair to good, and on Wednesday the chief pulmonary specialist at the hospital, Dr. James Walsh, said that Mr. Diomande still had "abnormal lung function." "I think Vado survived because he was such a fit and strong person to begin with," Dr. Walsh said.

A professional performer, Mr. Diomande even demonstrated his improved lung capacity by holding his breath for several seconds.

Dr. Walsh said that Mr. Diomande's condition was not contagious and that the public should not be fearful. "If you buy a drum from him, you are not going to get inhalation anthrax," he said. "If you shake his hand, you are not going to get inhalation anthrax."

After Mr. Diomande's doctors diagnosed anthrax, environmental cleanup crews detected anthrax spores at his Greenwich Village apartment and at the Brooklyn warehouse where he made the drums. The crews spent several weeks cleaning and decontaminating the sites, and though both locations have since been reopened, Ms. Diomande said many of the couple's possessions were destroyed during the cleaning process.

To help with Mr. Diomande's recovery, the couple are likely to delay a return to their fifth-floor walkup and stay with Ms. Diomande's brother in Jersey City, she said.

She also apologized to their neighbors and the tenants of the Brooklyn warehouse for the inconveniences during the cleanup.

"We feel for them because it's also happening to us, and we're hoping their lives will be restored as we hope with our lives," she said.

During nearly 40 minutes of questions, Mr. Diomande said that he would return to making drums but that he would take more precautions in the future, including always wearing a mask. He said he hoped to be dancing again within "maybe two weeks."

The United States Supreme Court refused to hear an appeal from The New York Times on Monday, allowing a libel suit by a former Army bioterrorism expert to go forward.

The suit, filed in 2003 by Steven J. Hatfill, accused Nicholas D. Kristof, an Op-Ed columnist for The Times, of implicating Dr. Hatfill in the unsolved anthrax attacks of 2001.

The suit was dismissed by a federal judge in Virginia in 2004. A divided three-judge panel of the United States Court of Appeals for the Fourth Circuit, in Richmond, Va., reinstated the case in July, and the full court, by a 6-to-6 vote, declined to rehear it in October.

The decisions to date have been preliminary, centering on whether Mr. Kristof's statements could be considered defamatory.

Judge Dennis W. Shedd, writing for the majority in the July decision, said "a reasonable reader of Kristof's columns likely would conclude that Hatfill was responsible for the anthrax mailings in 2001." But Judge J. Harvie Wilkinson III, dissenting from the October decision, said "the columns do not pin guilt on plaintiff, but instead urge the investigation of an undeniable public threat."

The trial court will now consider whether the statements were false and whether The Times was at fault for publishing them.

By WILLIAM J. BROAD
Published: September 26, 2006
The New York Times

Seeking to clear up public confusion, an F.B.I. official has reiterated the bureau’s judgment that the anthrax in the letter attacks five years ago bore no special coatings to increase its deadliness and no hallmarks of a military weapon.

In theory, that finding could widen the pool of potential suspects in the unsolved case since the perpetrator would have required less skill and could have worked with more commonplace materials. What started as the largest criminal investigation in American history now, five years later, appears to be stalled.

The statement by the Federal Bureau of Investigation official contradicts an array of assessments over the years about the anthrax attacks, which in late 2001 killed 5 people and sickened 17 others. Tainted letters were dropped into a mailbox in Princeton, N.J., sending anthrax to offices of several publications and two United States senators.

Soon after, a variety of public and private experts proclaimed the deadly spores to have been specially treated to enhance their ability to float in the air and reach deep into human lungs, where they could germinate and kill their host. Some experts called the anthrax military-grade.

But the bureau official, Douglas J. Beecher, a scientist at the F.B.I. Laboratory in Quantico, Va., disputed such claims as misguided in a recent journal article.

“A widely circulated misconception is that the spores were produced using additives and sophisticated engineering supposedly akin to military weapon production,” Dr. Beecher wrote in the August issue of Applied and Environmental Microbiology. “The persistent credence given to this impression fosters erroneous preconceptions, which may misguide research and preparedness efforts and generally detract from the magnitude of hazards posed by simple spore preparations.”

The F.B.I. declined to make available lead scientists in the inquiry.

The Hartford Courant and The Washington Post referred to the Beecher piece in recent articles.

William C. Patrick III, a scientist who once made germ weapons for the American military and is now a private consultant on biological defense, agreed with the F.B.I.’s assessment. “The material was good, but not weapons grade,” Mr. Patrick said in an interview. “You can’t make that in your basement. It requires sophisticated equipment.”

The misconceptions in the case began early, reinforced by edgy public officials and federal scientists struggling to assess an unfamiliar threat quickly. In Washington, the Armed Forces Institute of Pathology studied the anthrax and found what it believed to be added silica, a signature of military anthrax.

“This was a key component,” an institute official said at the time. “Silica prevents the anthrax from aggregating, making it easier to aerosolize.”

Last year, Edward G. Lake, a retired computer systems analyst in Racine, Wis., self-published a book, “Analyzing the Anthrax Attacks,” that documented the silica misunderstanding as well as many other federal and private blunders. “There were,” Mr. Lake said in an interview, “a lot of false assumptions.”

For its part, the F.B.I. has quietly but fairly consistently argued for a humdrum explanation. In November 2001, it said the culprit was probably a domestic loner with at least limited scientific expertise who was able to use laboratory equipment obtained for as little as $2,500.

Steven J. Hatfill, a former Army biodefense expert, came under intense scrutiny in the case even as he vigorously proclaimed his innocence. His extensive ties to the American military establishment seemed like circumstantial evidence of guilt among those who saw the anthrax as highly refined and possibly of weapons-grade.

In 2003, Dr. Hatfill sued the bureau and the Justice Department, saying leaks to the news media about him and the public description of him by Attorney General John Ashcroft as a “person of interest” in the case had violated his privacy rights. He also has defamation suits pending against The New York Times, Reader’s Digest and Vanity Fair.

Joseph Persichini Jr., acting assistant director of the Washington field office of the F.B.I., said in a recent statement that the bureau’s “commitment to solving this case is undiminished.”

“Despite the frustrations that come with any complex investigation,’’ he said, “no one in the F.B.I. has, for a moment, stopped thinking about the innocent victims of these attacks — nor has the effort to solve this case in any way been slowed.”

Nicholas Wade contributed reporting.

WASHINGTON, Oct. 23 — A federal magistrate judge has ordered The New York Times to disclose the identities of three confidential sources used by one of its columnists, Nicholas Kristof, for columns he wrote about the investigation of the deadly anthrax mailings of 2001.

The order, issued Friday by Magistrate Judge Liam O’Grady, requires the newspaper to disclose the identities of the three sources to lawyers for Dr. Steven J. Hatfill, who has brought a defamation suit against The Times. The order was disclosed Monday.

Catherine Mathis, a spokeswoman for The Times, said the newspaper would appeal the ruling.

Dr. Hatfill, a germ warfare specialist who formerly worked in the Army laboratories at Fort Detrick, Md., has asserted that a series of columns by Mr. Kristof about the slow pace of the anthrax investigation defamed him because they suggested he was responsible for the attacks.

Five people died in the attacks. Although the federal authorities identified Dr. Hatfill as a “person of interest” in the case, they have not charged him with any crimes.

At a deposition on July 13, Mr. Kristof declined to name five of his sources for the columns, but two have subsequently agreed to release him from his pledge of confidentiality. Judge O’Grady’s ruling identifies the remaining unnamed sources as two Federal Bureau of Investigation agents and a former colleague or friend of Dr. Hatfill at Fort Detrick.

The judge ruled that the laws of Virginia applied and that under that state’s law, reporters have only a qualified privilege to decline to name their sources that may be outweighed by other factors.

He wrote that for Mr. Hatfill to have a chance of meeting his burden of demonstrating that he was defamed by the columns, he “needs an opportunity to question the confidential sources and determine if Mr. Kristof accurately reported information the sources provided.”

Mr. Kristof wrote about a government scientist he initially referred to as Mr. Z, saying he had become the overwhelming focus of the investigation. In August 2002, he wrote that Dr. Hatfill had acknowledged he was Mr. Z. at a news conference in which he said he had been mistreated by the news media.

The lawsuit was originally dismissed by a federal judge in Virginia in 2004. A divided three-judge panel of the United States Court of Appeals for the Fourth Circuit in Richmond reinstated the case and the full appeals court, by a 6-to-6 vote, declined to overturn that ruling. The Supreme Court declined to intervene last March.

Judge O’Grady wrote: “The court understands the need for a reporter to be able to credibly pledge confidentiality to his sources. Confidential sources have been an important part of journalism, which is presumably why Virginia recognizes a qualified reporter’s privilege in the first place.”

He said Virginia law required the use of a three-part balancing test as to whether there is a compelling need for the information, whether the information is relevant and whether it may not be obtained any other way.

By NEIL A. LEWIS
Published: November 3, 2006

WASHINGTON, Nov. 2 — A federal judge in Virginia on Thursday upheld a ruling by a magistrate judge that The New York Times must disclose the identities of three sources used by Nicholas D. Kristof for columns he wrote on the deadly anthrax mailings of 2001.

The judge, Claude M. Hilton of Federal District Court, ruled that last month’s opinion was “not clearly erroneous or contrary to law.”

The order is part of a case of defamation brought against The Times by Stephen J. Hatfill, who asserts that columns by Mr. Kristof suggested he was responsible for the attacks.

The ruling is likely to make it more difficult for The Times to defend the lawsuit when the case goes to trial because a judge may instruct the jury to give less credibility to assertions that the columns had been based on legitimate and knowledgeable sources. Because it is a civil case rather than a criminal one, there is little chance of anyone from The Times facing the possibility of being jailed over contempt charges.

George Freeman, vice president and assistant general counsel for The Times, said Thursday’s ruling was disappointing, “given that the court recognized that confidential sources play an important role in good journalism, and that the court of appeals came very close to dismissing this case on a preliminary motion on the basis that the columns weren’t defamatory.”

“Though it may make defending the case tougher,” Mr. Freeman added, “we are confident that in the end, the columns will be vindicated.”

Five people died in the attacks. The authorities called Dr. Hatfill, who worked on germ warfare issues, a “person of interest” but have not charged him with any crimes.

By NEIL A. LEWIS
Published: November 18, 2006

WASHINGTON, Nov. 17 — A federal magistrate judge ruled on Friday that The New York Times may not rely in any way on information its columnist, Nicholas D. Kristof, may have received from two Federal Bureau of Investigation officials in its defense of a defamation suit brought by a former government scientist.

The judge, Liam O’Grady, issued the ruling as a sanction against The Times for refusing to disclose or force Mr. Kristof to disclose the identities of the two confidential F.B.I. sources he used in writing a series of columns about the investigation of the deadly anthrax mailings of 2001.

Dr. Stephen J. Hatfill, a germ warfare specialist who once worked in the Army laboratories at Fort Detrick, Md., has asserted in a lawsuit that the columns defamed him because they suggested he was responsible for the attacks.

In its filings, The Times has suggested that Mr. Kristof had numerous sources for the columns. Of those, Mr. Kristof initially refused to identify five, saying he had promised them confidentiality. He has since disclosed the identities of three, saying those sources recently released him from his pledge.

In issuing the ruling, Judge O’Grady rejected a series of harsher sanctions sought by Mr. Hatfill’s lawyers, including a request that the court impose a $25,000-a-day fine on The Times until it named the two F.B.I. officials.

Judge O’Grady issued his ruling from the bench in Alexandria, Va., where he sits and where the trial is scheduled to begin on Jan. 29. The ruling means that when Mr. Kristof testifies during the trial on behalf of The Times, he may not cite any information he may have received from the two confidential sources as substantiation for the columns.

How much of a setback the ruling is for The Times is unclear and probably depends on how much other substantiation Mr. Kristof and the newspaper may present to counter Dr. Hatfill’s assertions. Five people died in the anthrax attacks. Although federal authorities identified Dr. Hatfill as “a person of interest” in the case, they have not charged him with any crimes.

Mr. Kristof’s columns were about a government scientist he initially referred to as Mr. Z, someone he said had become the overwhelming focus of the investigation. In August 2002, he wrote that Dr. Hatfill had acknowledged he was Mr. Z at a news conference in which he said he had been mistreated by the news media.

Because the lawsuit is a civil action, not a criminal one, there was no consideration of anyone being ordered to jail as has happened in some recent criminal investigations. Instead, the judge said he fashioned the remedy to ensure that Dr. Hatfill was not disadvantaged by the use of information obtained by The Times from sources it would not identify and thus subject to examination.

Judge O’Grady had written earlier that for Dr. Hatfill to meet his burden of demonstrating he was defamed, he needed “an opportunity to question the confidential sources and determine if Mr. Kristof accurately reported information the sources provided.”

In preparation for the start of the trial, Dr. Hatfill was deposed Friday by lawyers for The Times.

The lawsuit was originally dismissed by a federal judge in Virginia in 2004, who ruled that the columns were not defamatory and only reported on the existence of an investigation. A divided three-judge panel of the United States Court of Appeals for the Fourth Circuit, in Richmond, Va., reinstated the case, and the full appeals court, by a 6-to-6 vote, declined to overturn that ruling. The Supreme Court declined to intervene last March.

WASHINGTON, Dec. 1 — The New York Times filed a motion with a federal judge on Friday asking him to dismiss a suit by a germ-warfare scientist who said a series of columns by Nicholas D. Kristof about the deadly anthrax mailings of 2001 defamed him.

The scientist, Stephen J. Hatfill, who formerly worked in the Army laboratories at Fort Detrick, Md., has said Mr. Kristof’s columns about the slow pace of the anthrax investigation defamed him because they suggested that he was responsible for the attacks.

In the motion filed Friday, lawyers for The Times asked Judge Claude M. Hilton of Federal District Court in Alexandria, Va., to dismiss the suit. The motion said Dr. Hatfill was a public figure because of his role in administering bioterrorism programs and speaking publicly about the issue.

As a public figure, The Times’s lawyers argued, Dr. Hatfill has a high burden to establish that he was defamed, including showing that the newspaper knowingly conveyed the idea that he was responsible for the attacks.

“No evidence indicates that The Times ever intended to imply plaintiff was in fact guilty of the anthrax mailings, and overwhelming evidence exists to the contrary,” the filing said.

The pleading also said that Dr. Hatfill could not demonstrate that the columns were published with “actual malice,” a standard for defaming public figures, because Mr. Kristof did not know whether Dr. Hatfill was responsible for the attacks, only that he was worthy of investigation.

Dr. Hatfill’s lawyers are scheduled to file a response this month in which they may well argue that he is not a public figure.

The legal papers filed by The Times included dozens of exhibits that made public for the first time internal F.B.I. memorandums about the inquiry, along with e-mail messages sent to and from Mr. Kristof.

One undated memorandum, apparently prepared to answer questions posed by the Senate Judiciary Committee, appears to have been written in the fall of 2002. It said that investigators interviewed Dr. Hatfill on four occasions in 2002 and that he consented to a polygraph examination in January 2002. Subsequently, the memorandum said, he declined additional polygraph examinations.

Another memorandum from the Federal Bureau of Investigation, dated Dec. 3, 2001, showed how the bureau investigated “persons of interest” in the case. The memorandum said the bureau had a three-tier system. Some people would “deserve the most active investigative attention” and others would be “screened out of consideration by the most reasonable and expedient manner available to include an interview.”

A brief in support of the motion to dismiss the case was also filed Friday, but its contents were not made public because it included material that parties in the case agreed to keep sealed. In addition, volumes of supplementary exhibits were filed but not released. The brief and some of the exhibits could be made public as early as Monday.

Five people died in the anthrax attacks. Although the federal authorities identified Dr. Hatfill as a “person of interest” in the case, they have not charged him with any crimes.

Mr. Kristof wrote about a government scientist he initially referred to as Mr. Z, saying he had become the overwhelming focus of the investigation. In August 2002, Mr. Kristof wrote that Dr. Hatfill had acknowledged that he was Mr. Z at a news conference in which he said the news media had mistreated him.

The case was initially dismissed by a trial judge who said the columns did not defame Dr. Hatfill but merely reported on the investigation. An appeals court reversed that ruling, saying a jury should decide the issue of defamation.

After the case went back to the trial court, a federal magistrate judge ruled that The Times had no basis to refuse to identify all of Mr. Kristof’s confidential sources. After The Times refused to identify two F.B.I. officials who were among the many sources, Magistrate Judge Liam O’Grady, also in Alexandria, ruled last month that The Times could not rely in any way on information from those sources in defending against Dr. Hatfill’s suit.

By NEIL A. LEWIS
Published: January 6, 2007

ALEXANDRIA, Va., Jan. 5 — A lawyer for a former government scientist who is suing The New York Times for defamation over a series of columns about the deadly anthrax mailings of 2001 said Friday in court that he was prepared to introduce an internal e-mail message from a senior Times editor that raised questions about one of the columns. 

 The lawyer, Mark A. Grannis, said the columns written by Nicholas D. Kristof about the federal investigation of the mailings unfairly damaged the reputation of his client, Dr. Stephen A. Hatfill, a former germ warfare scientist.

Dr. Hatfill’s lawyers have said the columns wrongfully suggested that he was responsible for the attacks.

Mr. Grannis told Judge Claude M. Hilton of Federal District Court here that if the trial proceeded he would introduce evidence including a May 23, 2002, message from Philip Taubman, then deputy editor of the editorial page, raising questions about a draft of a column by Mr. Kristof.

Beginning that spring, Mr. Kristof wrote a series of columns about a government scientist whom he initially referred to as Mr. Z., saying the scientist had become the overwhelming focus of the investigation. That August, Mr. Kristof wrote that Dr. Hatfill had acknowledged that he was Mr. Z. at a news conference in which he said the news media had mistreated him.

Mr. Grannis said he would introduce evidence of questions about the column posed by Mr. Taubman and others. The evidence from Mr. Taubman, the lawyer said, was a message saying the as-yet-unpublished column “pointed pretty much at the guy” and encouraging Mr. Kristof to take out some of the material that did that.

Mr. Grannis made his disclosure of the information that he has obtained in the discovery phase of the suit in a hearing on a Times motion to seek dismissal of the complaint.

The trial is scheduled to start Jan. 29. Judge Hilton did not say when he would rule.

The Times has argued that the columns were aimed at prodding the Federal Bureau of Investigation to pursue the anthrax case more vigorously and did not accuse Dr. Hatfill of being the person responsible for the mailings.

In writing about the investigation, Mr. Kristof’s ire was directed against federal officials for not moving swiftly to decide whether the scientist was guilty or innocent, the paper’s lawyers have said.

“His intent was to focus on the F.B.I.,” a lawyer for The Times, Lee Levine, told Judge Hilton.

Mr. Levine, of Levine Sullivan Koch & Schulz, told Judge Hilton that Mr. Hatfill was a public figure, or as someone recognized in libel and defamation law as a limited-purpose public figure, because of his involvement in the public debate about preparedness for a bioterrorist attack.

Mr. Levine said Dr. Hatfill had “voluntarily thrust himself into the vortex of that controversy” through his writings and speeches, confirmed by Dr. Hatfill’s complaints that he was easily identified as Mr. Z by many people in the field.

As a public figure Dr. Hatfill would have a far greater burden in his effort to win a defamation suit. To prevail, a public figure has to prove that the material was published with “actual malice,” that is with the knowledge that the statements were false or with reckless disregard as to whether they were false.

Lawyers for The Times also argued that neither Mr. Taubman’s message nor any other evidence put forward by Mr. Hatfill’s lawyers was proof that Mr. Kristof had acted with reckless disregard for the truth, the standard that Mr. Hatfill must meet if he is found to be a public figure.

The Times said that even if all of Mr. Hatfill’s assertions were true, he would not prevail and that therefore the judge should dismiss the case before trial. The message from Mr. Taubman, now Washington bureau chief for The Times, was released Friday afternoon by the lawyers for The Times. It read: “Nick, you’re still pointing pretty much at the guy. I think you need to lose the material I’ve marked in boldface.”

Mr. Taubman had marked two paragraphs referring to a middle-age American scientist with experience in producing bioweapons. The column, which appeared May 24, included the first of those two paragraphs but dropped the second, the messages showed. Although the essence of that message was pretty much as Mr. Grannis represented it in court, two other e-mail messages he cited were more ambiguous.

He said messages from Nicholas Wade, a former science editor at the paper and then a special projects writer, and Gail Collins, the editorial page editor, were critical of a column prepared for publication in July. Those messages, as disclosed by lawyers for The Times, raised more generalized suggestions.

Mr. Grannis said Mr. Wade’s message had said the column made it plausible to a reader that Mr. Kristof was pointing at Mr. Z as the culprit. But the message said it was plausible that Dr. Hatfill might have been involved in an earlier anthrax scare that was a hoax.

In her message, Ms. Collins said the column “looked fine to me” and asked how an anthrax mailing to The National Enquirer in Florida fit in.

Five people died in the attacks. Although federal authorities identified Dr. Hatfill as a “person of interest” in the case, he was not charged with any crimes. No one has been charged in the attacks.

WASHINGTON, Jan. 12 — A federal judge on Friday dismissed a suit against The New York Times by a former government scientist who said he was defamed by a series of columns about the deadly anthrax mailings in 2001.

The judge, Claude M. Hilton of Federal District Court in Alexandria, Va., granted a motion by The Times to dismiss the suit but did not provide an immediate explanation. He is expected to file a detailed written opinion in coming days.

It was the latest and, perhaps, final chapter in a suit that has gone to the Supreme Court.

The scientist, Dr. Stephen J. Hatfill, a specialist in biological weapons, had said in his suit that the columns by Nicholas D. Kristof about the anthrax mailings had defamed him.

Mr. Kristof wrote about a government scientist whom he initially identified as Mr. Z, saying he had become the overwhelming focus of the investigation. In August 2002, Mr. Kristof wrote that Dr. Hatfill, a former scientist at the Army bioweapons center at Fort Detrick, Md., had come forward and identified himself as Mr. Z and said the news media had treated him unfairly.

Five people died in the anthrax attacks. Although federal authorities identified Dr. Hatfill as a “person of interest,” he was never charged with any crime, and the attacks remain unsolved.

The Times argued in its dismissal motion that Dr. Hatfill was a public figure, at least for the purposes of the suit, in that he had thrust himself into the public debate about preparedness for a biological attack. That would present him with a far greater burden in showing that he was defamed and could, as the newspaper argued, prevent such a judgment.

The Times also argued that the columns did not blame Dr. Hatfill for the attacks, as he said in his suit. Instead, the paper’s lawyers said, the columns were aimed at pressing the Federal Bureau of Investigation to move more swiftly and either charge or clear Dr. Hatfill as a suspect.

Judge Hilton had dismissed the suit earlier, saying that no defamation had occurred. A three-judge appeals panel voted, 2 to 1, to reinstate the suit, saying a jury should decide whether the columns were defamatory.

The full appeals court, based in Richmond, Va., split, and the Supreme Court refused to intervene.

Judge Hilton’s latest dismissal, when his opinion is published, is expected to rest on a fuller argument than the last time and could thus be less vulnerable to being overturned. It is likely to deal with the issues raised in The Times’s dismissal motion and Dr. Hatfill’s response, including the question of whether he is a public figure for the purposes of defamation law.

Whether there is any leeway for Dr. Hatfill to mount an appeal as he did before would depend on how Judge Hilton fashions his ruling.

A lawyer for Dr. Hatfill, Mark A. Grannis, said, “Obviously we can’t make any statements as to what we’ll do until we see the ruling.”

Mr. Grannis said he did not believe that the case was over.

“It has always been our position,” he said, “that the evidence of defamation was extremely strong and Mr. Kristof fabricated parts of his column to falsely implicate Dr. Hatfill in the anthrax attacks.”

David E. McCraw, a lawyer for The Times, said in a statement: “We are gratified by the judge’s ruling today. In making our summary judgment motion, we believed that the plaintiff had failed to come up with the evidence necessary to bring this case to trial, and we are pleased that the court agreed.”

Mr. McCraw said the case had required a significant investment of time and money on the part of the newspaper, “but in the end, the law of defamation worked the way it was supposed to, by protecting aggressive, important journalism.”

By STEPHEN LABATON
Published: February 2, 2007

WASHINGTON, Feb. 1 — A federal judge who dismissed a defamation lawsuit against The New York Times acted after concluding that the scientist who brought the case, a bioterrorism expert investigated over deadly anthrax mailings in 2001, was a public official and could not show that the newspaper had knowingly published false information.

In an opinion released Thursday, the judge, Claude M. Hilton of the Federal District Court in Alexandria, Va., laid out the reasons for his order last month dismissing a long-running case brought by Steven J. Hatfill, a specialist in biological weapons. Dr. Hatfill’s lawsuit said a series of columns by Nicholas D. Kristof about the anthrax mailings had defamed him.

Mark A. Grannis, a lawyer for Dr. Hatfill, said Judge Hilton’s opinion was unsurprising and was not the last word in the case.

“The opinion is more or less what we expected, given the judge’s earlier statements,” Mr. Grannis said. “We will appeal, and we expect to prevail.”

Mr. Kristof wrote about a government scientist whom he initially identified as Mr. Z, saying this scientist had become the overwhelming focus of the investigation into the anthrax attacks. Then, in August 2002, Mr. Kristof wrote that Dr. Hatfill, formerly with the Army bioweapons center at Fort Detrick, Md., had come forward to identify himself as Mr. Z and say the news media had treated him unfairly.

Five people died in the anthrax attacks. Federal authorities identified Dr. Hatfill as a “person of interest” in the investigation but never charged him with any crime. The attacks remain unsolved.

Judge Hilton’s opinion, which was dated Tuesday, said Dr. Hatfill could be considered both a “public official” and a “public figure” and therefore would have to meet a higher burden of proof than would a private figure in order to prevail in a defamation suit. Under that higher burden, a public figure bringing suit must demonstrate that the writer acted with “actual malice” — that is, either knew that what he was writing was false or had “a high degree of awareness” that it probably was.

The judge said Dr. Hatfill was a public official because even after he left his formal government position, he continued to perform official functions as a federal contractor. At the time Mr. Kristof wrote about the case, Dr. Hatfill was receiving federal money to work on national defense programs, the judge said.

The opinion said Dr. Hatfill was also a public figure, holding himself out as an expert on bioterrorism and granting interviews to a variety of news organizations.

Judge Hilton described at length the government’s inquiry into the case and its focus on Dr. Hatfill. He disclosed that the F.B.I. had searched Dr. Hatfill’s car and a condominium owned by his girlfriend and had seized several items, including “notes regarding the anthrax mailings, a spinner flask of anthrax stimulant and a container of Cipro.” A spinner flask could be used to study the properties of anthrax, and Cipro is an antibiotic used to treat a variety of ailments, including anthrax poisoning.

By ADAM LIPTAK
Published: August 14, 2007

Five reporters must testify about their law enforcement sources in a former Army scientist’s lawsuit against the Justice Department, a federal judge in Washington ruled yesterday.

The suit, filed by Steven J. Hatfill, a bioterrorism expert, contends that the government violated the federal Privacy Act by providing journalists with information about him in the F.B.I.’s investigation of the deadly anthrax mailings in 2001.

The reporters — Michael Isikoff and Daniel Klaidman of Newsweek; Allan Lengel of The Washington Post; Toni Locy, formerly of USA Today; and James Stewart, formerly of CBS News — have acknowledged receiving information from the Justice Department and the F.B.I. about Dr. Hatfill, the judge, Reggie B. Walton, wrote in his decision yesterday. But they have refused to name their sources.

Judge Walton, of the Federal District Court in Washington, said Dr. Hatfill was entitled to the sources’ names because “the information sought is clearly central to his Privacy Act claims.”

“Denying civil litigants access to the identity of government officials who have allegedly leaked information to reporters would effectively leave Privacy Act violations immune from judicial condemnation,” Judge Walton wrote, “while leaving potential leakers virtually undeterred from engaging in such misbehavior.”

The reporters are not defendants in the suit but are likely to face contempt sanctions if they fail to comply with Judge Walton’s order. Lawyers for Mr. Lengel and Ms. Locy and a spokeswoman for Mr. Isikoff and Mr. Klaidman declined to comment yesterday. A lawyer for Mr. Stewart did not respond to a request for comment.

In April, Judge Walton referred the parties to mediation in an effort to settle the case. A separate lawsuit by Dr. Hatfill against The New York Times, claiming that columns by Nicholas D. Kristof had defamed him, was dismissed by a federal judge in Virginia in January. Dr. Hatfill has appealed.

Last year, the government and five news organizations, including The Times, paid Wen Ho Lee, an atomic scientist once suspected of espionage, $1,645,000 to settle what Judge Walton, in his decision yesterday, called a “strikingly similar” case.

By THOMAS KAPLAN
Published: September 6, 2007

NEW HAVEN, Sept. 5 — Two people in Danbury, Conn., have contracted anthrax, probably from animal hides brought from Africa to make drums, the authorities said on Wednesday.

A spokesman for the New Haven office of the Federal Bureau of Investigation said the cases did not appear to be terrorism-related.

Officials would not release the names of the patients, who are in the same family, but the owner of the home where the anthrax was found, Donald Lombardo, identified the tenant as Ase-AmenRa Kariamu, The Associated Press reported.

Mr. Kariamu is the director of a West African drumming program at the Danbury Music Center.

Mayor Mark D. Boughton of Danbury said the house was being used to store untanned animal hides obtained from areas of the world where anthrax is known to be common.

At least one of the patients is believed to have contracted cutaneous anthrax from working with the hides, Mayor Boughton said. Local and state officials were examining the patient’s house in an effort to pinpoint the source of the anthrax, Mayor Boughton said.

It is the second time in two years that African drummers in the metropolitan region have contracted anthrax.

In both cases, untanned hides for drums were believed to be the source.

The two Danbury patients are recovering, said William Gerrish, a spokesman for the Connecticut Department of Public Health.

Officials are in the process of contacting their relatives and acquaintances to determine if anyone else was exposed, Mr. Gerrish said.

Cutaneous anthrax is rare and is not contagious.

“We certainly recognize that any time anthrax is involved, it can generate concern,” Mr. Gerrish said. “But we do not believe that there is a threat to the general public.”

Cutaneous anthrax, the most common type, is an infection of the skin and can be treated with common antibiotics, according to the Centers for Disease Control and Prevention.

Only one or two cases occur annually in the United States, Bernadette Burden, a spokeswoman for the centers, said in a telephone interview.

The more serious form is inhalation anthrax. It was responsible for five deaths in the United States, including one in Connecticut, when anthrax spores were sent through the mail in the months after the 9/11 attacks.

Ottilie W. Lundgren, 94, who lived in Oxford, Conn., about 20 miles east of Danbury, was one of the five victims of that attack, which spread panic and crippled the postal system for several months. Seventeen others were sickened nationwide.

Mayor Boughton said one of the two infected people in Danbury went to a local hospital in mid-August for treatment and later saw a number of specialists. A test for anthrax came back positive on Tuesday morning, Mayor Boughton said.

Since the source of the infection was uncertain at that point, federal, state and local authorities became involved, the mayor said. Concern subsided when officials determined that the hides on the drums were likely to blame, he said.

“It’s what we call a naturally occurring case of anthrax,” Mayor Boughton said. “It’s not related to terrorism.”

Nor is it unique. In February 2006, a 44-year-old Greenwich Village drummer contracted the more serious inhalation anthrax while using unprocessed animal skins to make drums.

The authorities believe he inhaled anthrax spores while covering a drum with goat skin he bought in the Ivory Coast, where he was born and raised.

The drummer, Vado Diomande, spent more than a month in the hospital and lost 45 pounds as he fought the disease.

He survived and vowed to return to his dancing and drum-making.

Anthrax spores are formed by naturally occurring bacteria and can be found in soil, according to the Centers for Disease Control. Animals who ingest contaminated soil can then pass the disease to people who handle their hides or eat undercooked meat.

Naturally occurring anthrax is rare in the United States but much more prevalent in other parts of the world, including many developing countries and much of sub-Saharan Africa.

Symptoms of cutaneous anthrax, which accounts for 95 percent of all anthrax cases, include swelling of the skin and itchiness, experts said.

It is not usually fatal when treated, unlike inhalation anthrax, which is often fatal.

By THOMAS KAPLAN
Published: September 6, 2007

NEW HAVEN, Sept. 6 — A property in Danbury, Conn., where two people are believed to have contracted anthrax is contaminated with spores of the potentially fatal disease, state officials said today.

In the past 24 hours, officials conducted tests of 27 samples gathered in a three-story home on the property and in a barn in the backyard. Five samples from the barn tested positive for anthrax, as did one from the door to the house, said Rachael Sunny, a spokeswoman for the Connecticut Department of Environmental Protection.

A resident of the property and one of his family members probably contracted anthrax after coming in contact with untreated animal hides brought from Africa to make drums, the authorities said on Wednesday. Terrorism is not suspected.

Just after noon today, a crew was preparing to enter the house and collect 12 additional samples, Ms. Sunny said from the scene in Danbury. The department expects it to take at least 24 hours to test those samples.

Meanwhile, several nearby residences have since been voluntarily evacuated, and nearly a mile of Padanaram Road, where the house is located, remains closed.

But there is no immediate health concern for neighbors, Ms. Sunny said. Some neighbors chose to evacuate merely because it was more convenient to sleep elsewhere as crews worked all night nearby, she said.

Officials would not release the names of the patients, who are in the same family, but the owner of the home where the anthrax was found, Donald Lombardo, identified the tenant as Ase-AmenRa Kariamu, The Associated Press reported.

Mr. Kariamu is the director of a West African drumming program at the Danbury Music Center.

Mayor Mark D. Boughton of Danbury said the house was being used to store untanned animal hides obtained from areas of the world where anthrax is known to be common. At least one of the patients is believed to have contracted cutaneous anthrax from working with the hides, Mayor Boughton said.

It is the second time in two years that African drummers in the metropolitan region have contracted anthrax. In both cases, untanned hides for drums were believed to be the source.

The two Danbury patients are recovering, said William Gerrish, a spokesman for the Connecticut Department of Public Health.

“We certainly recognize that any time anthrax is involved, it can generate concern,” Mr. Gerrish said. “But we do not believe that there is a threat to the general public.”

Cutaneous anthrax, the most common type, is a non-communicable infection of the skin and can be treated with common antibiotics, according to the Centers for Disease Control and Prevention.

Only one or two cases occur annually in the United States, Bernadette Burden, a spokeswoman for the centers, said in a telephone interview.

The more serious form is inhalation anthrax. It was responsible for five deaths in the United States, including one in Connecticut, when anthrax spores were sent through the mail in the months after the attacks of Sept. 11, 2001.

In February 2006, a 44-year-old Greenwich Village drummer contracted the more serious inhalation anthrax while using unprocessed animal skins to make drums.

The authorities believe he inhaled anthrax spores while covering a drum with goat skin he bought in the Ivory Coast, where he was born and raised.

The drummer, Vado Diomande, spent more than a month in the hospital and lost 45 pounds as he fought the disease.

He survived and vowed to return to his dancing and drum-making.

Anthrax spores are formed by naturally occurring bacteria and can be found in soil, according to the Centers for Disease Control. Animals who ingest contaminated soil can then pass the disease to people who handle their hides or eat undercooked meat.

Naturally occurring anthrax is rare in the United States but much more prevalent in other parts of the world, including many developing countries and much of sub-Saharan Africa.

Symptoms of cutaneous anthrax, which accounts for 95 percent of all anthrax cases, include swelling of the skin and itchiness, experts said.

It is not usually fatal when treated, unlike inhalation anthrax, which is often fatal.

Published: February 20, 2008

WASHINGTON — A federal judge found a former reporter for USA Today in contempt of court on Tuesday for refusing to name her confidential sources who had discussed a former Army scientist’s possible role in the 2001 anthrax attacks.

The reporter, Toni Locy, now faces fines of up to $5,000 a day for refusing to comply with an earlier order issued by the judge, Reggie B. Walton. Judge Walton said he would decide in coming days whether a second former reporter, Jim Stewart, should also be held in contempt of court for refusing to reveal the sources for his accounts on the anthrax inquiry, broadcast on CBS News.

The two journalists are being pressed to reveal their sources by Dr. Steven J. Hatfill, a onetime bioterrorism expert for the Army, who is suing the federal government, saying his reputation was ruined by leaks to the news media from law enforcement officials linking him to the attacks. In 2002, the F.B.I. and John Ashcroft, then the attorney general, described Dr. Hatfill as a “person of interest” in the investigation into the attacks, which killed five people and remain unsolved.

Judge Walton said Ms. Locy’s testimony was important to help Dr. Hatfill pursue his civil lawsuit against the government, but advocates for the news media said his order was the latest of recent rulings that could hamper the work of journalists.

“Of all the federal court sanctions on reporters for refusing to reveal confidential sources over the past several years, this is perhaps the most disturbing,” said Lucy A. Dalglish, executive director of the Reporters Committee for Freedom of the Press.

“Toni Locy is being punished for doing what reporters are supposed to do: making sure important information gets to the public about whether the government had the investigation into a major public health threat under control,” Ms. Dalglish said.

Ms. Locy has declined to identify the sources she relied on in three articles for USA Today about the investigation. The articles discussed Dr. Hatfill’s role in the investigation and raised questions about the strength of the evidence against him.

Ms. Locy declined after the hearing to discuss any details of the case but said that the judge’s order could make it difficult for journalists to report on the status of any law enforcement investigation, even a high-profile one, “until someone is charged, tried and convicted.”

“I’m concerned about the ramifications of this order for all journalists, beyond just me,” said Ms. Locy, who now teaches journalism at West Virginia University.

In holding Ms. Locy in contempt, Judge Walton said he would impose fines beginning at $500 a day for seven days, then escalating to $1,000 a day for seven days, then $5,000 a day for seven days. He would then consider other options, which lawyers said could include jail time.

Judge Walton said he would soon rule on whether his order would be delayed pending a probable appeal by Ms. Locy.

Ms. Locy and Mr. Stewart are the only journalists still facing contempt citations in the case. Because of procedural problems and other issues, the court previously threw out subpoenas seeking testimony from a number of other journalists, including Nicholas D. Kristof, a columnist for The New York Times, who first wrote in 2002 about a mysterious Army scientist he called Mr. Z, whom he later identified as Dr. Hatfill. A defamation suit against Mr. Kristof was dismissed last year, a decision now under appeal.

Judge Walton had some cautionary words for journalists on Tuesday, but he saved his harshest judgments for the unidentified officials who linked Dr. Hatfill to the anthrax investigation in the news media.

“There’s not a scintilla of evidence to suggest Dr. Hatfill had anything to do with it,” the judge said, yet the public notoriety has “destroyed his life.” 

Every day, newspapers publish articles like the ones that have gotten Toni Locy in trouble: she quoted law enforcement officials, their names kept secret, about a person under investigation in an unsolved crime.

But there was nothing ordinary about the crime — the anthrax attacks in 2001 — or the fallout for Ms. Locy, a reporter who wrote about the case for USA Today. She has become one of the rare reporters who risk serious punishment for refusing to reveal confidential sources, and even in that exclusive company, her story is extraordinary.

A federal judge in Washington, Reggie B. Walton, wants her to name sources who might have had nothing to do with her articles. He has ordered her to pay fines up to $5,000 a day if she continues to withhold the names. And he has ordered that she pay the fines herself, prohibiting the newspaper from paying for her.

The actions against Ms. Locy, 48, are unlike any taken by an American court, according to First Amendment lawyers, media associations and companies that have petitioned the court on her behalf. They say that Judge Walton’s decision last month to hold her in contempt of court sets a precedent that would chill the routine workings of the press.

The contempt order has been stayed pending an appeal to the Court of Appeals for the District of Columbia, which will hear arguments on May 9.

“This is an unprecedented fishing expedition to expose people without any reason to think they have any relevant information,” said Lucy A. Dalglish, executive director of the Reporters Committee for Freedom of the Press. “Never has a court specified that the sanctioned person has to pay the fines herself, and fines of this magnitude are almost unheard of.”

Judge Walton has described the issue as straightforward. The plaintiff in a lawsuit needs the information, he has said on the bench and in court papers, and a contempt finding is meaningless without some coercive power. He set her fine to increase over time, up to $5,000 a day after the second week in contempt.

The plaintiff is Steven J. Hatfill, a scientist who was considered a suspect in the anthrax attacks, though no one has been charged. He sued the federal government, claiming that in talking about him to reporters, officials violated the federal Privacy Act.

Judge Walton ordered Ms. Locy to reveal her unnamed sources for two articles she wrote in 2003.

Ms. Locy, now an assistant professor of journalism at West Virginia University, says she cannot recall which government officials gave the information. So the judge ordered her to name all sources with whom she might have discussed the case.

She says she had 10 to 12 such sources, people with whom she also discussed subjects like the hunt for Osama bin Laden and the treatment of prisoners at Guantánamo Bay. Under Judge Walton’s order, she said, “folks who helped me on far more sensitive stories than the two at issue in this case could be exposed.”

But Judge Walton said that “the identity of those who did not provide information about Dr. Hatfill will remain confidential to all other than Dr. Hatfill and his attorneys.”

Many states have laws shielding reporters from having to divulge sources in most circumstances, but there is no similar federal law. Last year, the House of Representatives passed a shield bill, 398 to 21, but a weaker version stalled in the Senate.

Representative Mike Pence, Republican of Indiana and the author of the House bill, lately has cited Ms. Locy’s plight as proof that a shield law is needed. Her case “is the biggest bullet in the gun,” said Matt Lloyd, a spokesman for the congressman.

Ms. Locy contends that much of the information in her articles first came to her from one of Dr. Hatfill’s own lawyers and that law enforcement figures only confirmed it.

More than many of her competitors, she wrote skeptically about the government’s focus on him. She compared the treatment of Dr. Hatfill to that of Richard Jewell, a suspect in the 1996 Olympics bombing in Atlanta, and pointed out that “Jewell was cleared, marking one of the most humbling chapters in F.B.I. history.”

By CLARK HOYT
Published: April 20, 2008
The New York Times

THE push for a federal shield law to help journalists protect the identities of confidential sources got a big boost last week when John McCain, the Republican presidential candidate, endorsed it in Washington at a convention of the nation’s newspaper editors and publishers.

The Democratic candidates, Hillary Clinton and Barack Obama, are also on board, and supporters of the proposal, which is strongly opposed by the Bush administration, are optimistic that success is near. The bill awaits Senate action after the House passed its version last October by a vote of 398 to 21.

Times reporters have had more than their share of recent court struggles to protect confidential sources, the latest being James Risen, who is fighting a grand jury subpoena for testimony involving a 2006 book he wrote on the C.I.A. But the journalist in the most immediate jeopardy is Toni Locy.

Locy, a former reporter for USA Today, is facing the choice of personal financial ruin or surrendering the names of as many as a dozen sources who might — or might not — have given her information about Steven J. Hatfill, a “person of interest” in the investigation of the 2001 anthrax attacks that killed five people, injured 17 and terrorized the nation. It is not clear that a federal shield law can arrive in time — or in a form — to help her.

Hatfill, a former government researcher who specialized in germ warfare, is suing the Justice Department and the F.B.I. because he says leaks to the news media about the anthrax investigation violated the federal Privacy Act and destroyed his reputation. (He also filed a defamation suit against The New York Times for columns by Nicholas D. Kristof that first identified him only as “Mr. Z.” The trial judge dismissed that suit, and Hatfill is appealing the decision.)

United States District Judge Reggie B. Walton has ordered Locy to identify her sources or pay heavy fines, escalating to $5,000 a day. He has decreed that no one can help her with them — not USA Today, her family or her students at West Virginia University, who had offered to organize a bake sale. Locy teaches media law and public affairs reporting and will be moving this fall to Washington and Lee University.

“I really do love the law,” she told me, even as she faces the prospect of bankruptcy at its hands. Locy said she has little equity in the three-bedroom home she bought last year, her first, and is making car payments on a 2007 Nissan Murano. Her savings have been drained to help pay medical expenses for a niece with a serious birth defect, and all that remains is a 401 (k) retirement plan that would be wiped out in little time under Walton’s order. She said she is not sleeping well.

A federal appeals court stayed the fine and is scheduled to hear arguments on the case on May 9.

Locy covered the Justice Department for USA Today from 2000 through 2005. The newspaper’s editor, Ken Paulson, described her as “a tenacious and hard-working reporter.”

In May 2003, she was asked to write an update on the anthrax case, which was then two years old and still unsolved, as it remains today. The news media had already reported that Hatfill was a focus of the investigation, that his apartment had been searched three times and that he had failed lie detector tests. Attorney General John Ashcroft had gone on “The Early Show” on CBS the previous August and identified Hatfill as “a person of interest,” a designation that has not been removed by the Justice Department, even though no charges have been brought against Hatfill in all the years since.

Locy wrote skeptically about the investigation, comparing Hatfill to Richard Jewell, the former security guard who was wrongly implicated in the bombing at the 1996 Atlanta Olympics. She said that investigators — but not all of them — believed Hatfill was behind the anthrax attacks. Two unidentified sources said the evidence against him was largely circumstantial.

Locy said that she talked with one of Hatfill’s lawyers before writing the article and that he praised it afterward as fair coverage, never raising Privacy Act problems because of what the unidentified sources had told her. As her desk became cluttered, she said, she tossed away her notes. Today, she said, she cannot remember who told her what about Hatfill.

Judge Walton has criticized Locy for not keeping her notes, as though she should have anticipated a lawsuit and that she would be called to testify. At a hearing in February, he also seemed skeptical that Locy could not remember five years later what her sources had said. “I’m not suggesting that Ms. Locy would not be truthful,” he said, “but it would be very convenient for reporters in this situation to just say, ‘I don’t recall.’ ”

Locy said she had 10 to 12 sources at the Justice Department and the F.B.I. who talked with her about the anthrax investigation — and about many other stories she covered during her four years on the beat. Walton said she had to identify all of them so that Hatfill’s attorneys could question them about whether they gave her information about their client. The judge then imposed the stiff fines to coerce her. Her lawyers argue that they amount to unlawful punishment because she has not been found guilty of criminal contempt of court.

Two of Locy’s sources did agree to come forward, and they said they could not remember what they had told her.

Locy’s lawyers contend that Hatfill does not need her sources, saying his lawyers told the judge in January that they were ready to proceed to trial and believed they had a strong case. Mark Grannis, a lawyer for Hatfill, said Locy’s sources were important but that getting a trial this year, before memories fade even more, was more important than waiting out a long fight to get her to give up the names.

There are two competing interests here: the right of an individual who believes he has been wronged to sue for damages, and a reporter’s need to keep promises of confidentiality to sources who provide information for stories of vital public interest. If something close to the House version of the shield law were to become reality and be applied to this case, Locy would be off the hook, because the reporter’s privilege in most civil cases like Hatfill’s would be absolute. But the Senate might include a balancing test — to let a judge decide which interest was more compelling in each case — meaning Locy could still be in hot water. Walton said he thinks government employees should be fired for talking about a criminal investigation.

In the end, whatever damage was done to Steven Hatfill’s reputation was not done by Locy’s articles, played inside USA Today long after he was swept up in the case by intense media coverage and the attorney general’s statement. Hatfill can still have his day in court without her sources. Breaking Toni Locy to set an example for journalists and as a warning to government officials not to talk confidentially with reporters sends exactly the wrong signals in an era of increasing government secrecy. Her case is a powerful argument for a federal shield law.

WASHINGTON — The Justice Department announced Friday that it would pay $4.6 million to settle a lawsuit filed by Steven J. Hatfill, a former Army biodefense researcher intensively investigated as a “person of interest” in the deadly anthrax letters of 2001.

The settlement, consisting of $2.825 million in cash and an annuity paying Dr. Hatfill $150,000 a year for 20 years, brings to an end a five-year legal battle that had recently threatened a reporter with large fines for declining to name sources she said she did not recall.

Dr. Hatfill, who worked at the Army’s laboratory at Fort Detrick in Frederick, Md., in the late 1990s, was the subject of a flood of news media coverage beginning in mid-2002, after television cameras showed Federal Bureau of Investigation agents in biohazard suits searching his apartment near the Army base. He was later named a “person of interest” in the case by then Attorney General John Ashcroft, speaking on national television.

In a news conference in August 2002, Dr. Hatfill tearfully denied that he had anything to do with the anthrax letters and said irresponsible news media coverage based on government leaks had destroyed his reputation.

Dr. Hatfill’s lawsuit, filed in 2003, accused F.B.I. agents and Justice Department officials involved in the criminal investigation of the anthrax mailings of leaking information about him to the news media in violation of the Privacy Act. In order to prove their case, his lawyers took depositions from key F.B.I. investigators, senior officials and a number of reporters who had covered the investigation.

Mark Grannis, a lawyer for Dr. Hatfill, said his client was pleased with the settlement.

“The good news is that we still live in a country where a guy who’s been horribly abused can go to a judge and say ‘I need your help,’ and maybe it takes a while, but he gets justice,” Mr. Grannis said.

The settlement, Mr. Grannis said, “means that Steven Hatfill is finally an ex-person of interest.”

In a written statement, Mr. Grannis and Dr. Hatfill’s other lawyers said, “We can only hope that the individuals and institutions involved are sufficiently chastened by this episode to deter similar destruction of private citizens in the future — and that we will all read anonymously sourced news reports with a great deal more skepticism.”

The lawyers will take their fee out of the settlement, which will pay out $5.8 million over 20 years. The $4.6 million figure is the cost of the annuity to the government.

The settlement called new attention to the fact that nearly seven years after the toxic letters were mailed, killing five people and sickening at least 17 others, the case has not been solved.

A Justice Department spokesman, Brian Roehrkasse, said in a statement that the government admitted no liability but decided settlement was “in the best interest of the United States.”

“The government remains resolute in its investigation into the anthrax attacks, which killed five individuals and sickened others after lethal anthrax powder was sent through the United States mail,” Mr. Roehrkasse said.

An F.B.I. spokesman, Jason Pack, said the anthrax investigation “is one of the largest and most complex investigations ever conducted by law enforcement” and is currently being pursued by more than 20 agents of the F.B.I. and the Postal Inspection Service.

“Solving this case is a top priority for the F.B.I. and for the family members of the victims who were killed,” Mr. Pack said.

But Representative Rush Holt, a New Jersey Democrat whose district was the site of a postal box believed to have been used in the attacks, said he would press Robert S. Mueller III, director of the F.B.I., for more answers about the status of the case.

“As today’s settlement announcement confirms, this case was botched from the very beginning,” Mr. Holt said. “The F.B.I. did a poor job of collecting evidence, and then inappropriately focused on one individual as a suspect for too long, developing an erroneous theory of the case that has led to this very expensive dead end.”

Dr. Hatfill subpoenaed Washington journalists to try to learn which federal officials had spoken to the news media about the case against him in possible violation of federal privacy laws.

Toni Locy, a former legal affairs reporter for USA Today who wrote several articles about the case, was held in contempt of court, facing fines of up to $5,000 a day from Judge Reggie Walton over her refusal to name her sources, and her case is pending before an appeals court. Ms. Locy said Friday that she was relieved by the developments but that it was too soon to celebrate.

“I hope this means that this ordeal is over and that I can get on with my life,” said Ms. Locy, who will begin teaching legal reporting at Washington and Lee University in the fall.

She said Dr. Hatfill’s lawyers said they no longer needed her testimony, though she had not been told whether the contempt order against her had been lifted.

The outcome differed significantly from the settlement of a similar case involving Wen Ho Lee, a former nuclear scientist once suspected of espionage. In that case, five news organizations joined the government’s settlement, agreeing to pay a total of $750,000 to prevent their reporters from having to testify about their sources.

Ms. Locy said that a federal mediator had tried to get Gannett, which owns USA Today, to negotiate some type of settlement with Dr. Hatfill’s lawyers, but that it had refused

She called the result an important affirmation of journalists’ ability to use confidential sources in gathering material on important news stories. “I protected my sources, and that’s important,” she said.

Dr. Hatfill also sued The New York Times and the columnist Nicholas D. Kristof, saying that columns Mr. Kristof wrote about the case had libeled him by suggesting that he might be the anthrax mailer. That lawsuit was dismissed last year, but Dr. Hatfill has appealed the dismissal.

The former Army scientist also sued Vanity Fair and the author of an article about the case in the magazine, Donald Foster, as well as Reader’s Digest, which published a condensed version. That case was settled last year on confidential terms.

Dr. Hatfill, 54, grew up in Illinois but studied medicine in Rhodesia, now Zimbabwe. After returning to the United States in the early 1990s, he worked at the National Institutes of Health and the United States Army Medical Research Institute for Infectious Diseases at Fort Detrick. In applying for those jobs, he claimed to have had a Ph.D. from a South African university that his lawyers later admitted he had not earned.

He did training on bioterrorism for the F.B.I., Central Intelligence Agency and Defense Intelligence Agency and trained to be a bioweapons inspector for the United Nations, though he never began the job.

After Dr. Hatfill came under suspicion in the anthrax case in 2002, an F.B.I. surveillance team began following him everywhere, and a small motorcade sometimes trailed his car around Washington.

In May 2003, an F.B.I. surveillance car ran over Dr. Hatfill’s foot in Georgetown as he approached the car to take the driver’s picture. He was given a ticket for “walking to create a hazard” and was fined $5.

David Stout contributed reporting from Washington.

WASHINGTON — A federal appeals court on Monday unanimously affirmed the dismissal of a suit against The New York Times by a former government scientist who had asserted that he was defamed by a series of columns about the deadly anthrax mailings of 2001.

The three-judge panel said that a federal trial court judge had correctly granted The Times’s motion to dismiss the suit brought by the scientist, Steven J. Hatfill, a specialist in biological weapons.

The author of the columns, Nicholas D. Kristof, initially wrote about a government scientist he identified as Mr. Z, saying he was the overwhelming focus of the investigation into the anthrax mailings, in which five people died. In August 2002, Mr. Kristof identified Dr. Hatfill as Mr. Z, saying he had come forward and identified himself to the news media as the person being written about.

Although the federal authorities had deemed Dr. Hatfill a “person of interest” in the investigation, he was never charged with any crime and the attacks remain unsolved.

Writing for the appeals court, based in Richmond, Va., Judge Paul V. Niemeyer said that the trial court had been correct to rule that Dr. Hatfill was a public figure and thus had to meet an especially high standard to prevail in his suit against The Times. Under a landmark 1964 Supreme Court ruling, a public figure must demonstrate that a publication acted with “actual malice” to succeed in a defamation suit. That meant that Dr. Hatfill had to show that The Times knew or suspected that any suggestion he was involved in the anthrax attacks was false and published the articles anyway.

The appeals court opinion, joined by Judges M. Blane Michael and C. Arlen Beam, said that Dr. Hatfill was a public figure in the context of bioterrorism because he had through numerous news media interviews “voluntarily thrust himself into the debate” about the nation’s preparedness to deal with events like the anthrax mailings.

Last month, the Justice Department agreed to pay $4.6 million to settle a lawsuit in which Dr. Hatfill claimed that law enforcement officials had improperly leaked information about him to news outlets in connection with the anthrax investigation.

By CHARLIE SAVAGE
Published: August 2, 2008

WASHINGTON – For six years, Steven J. Hatfill has sought in public and in court to clear his name after being named a “person of interest” in the 2001 anthrax investigation.

On Friday, the disclosure that a former colleague of Dr. Hatfill committed suicide after investigators prepared to indict him provided the clearest indication yet that Dr. Hatfill may finally achieve his goal.

The Justice Department, which has not publicly exonerated the former Army scientist, would not comment about the case on Friday. But by all indications, investigators have lost interest in Dr. Hatfill.

A lawyer familiar with the investigation of Bruce E. Ivins, Dr. Hatfill’s former colleague at the Army’s bio-defense labs at Fort Detrick, who died earlier this week after ingesting an overdose of prescription painkillers, said that Dr. Ivins was expected to be indicted alone.

The former Army scientist spent years in the glare of official suspicion after someone sent envelopes containing anthrax powder to government officials and news media outlets in late 2001.

Those suspicions became public in mid-2002, when television crews filmed agents from the Federal Bureau of Investigation wearing biohazard suits as they raided Dr. Hatfill’s apartment. Then-Attorney General John Ashcroft later described Dr. Hatfill as a “person of interest” in the investigation.

Dr. Hatfill gave a tearful press conference in August 2002 denying any involvement in the attacks and contending that he had been smeared by F.B.I. leaks and irresponsible reporting.

But he would spend years under the microscope. He accused investigators of tipping off the media in advance of the search of his home, and later of conducting constant surveillance of him. His home phone was wiretapped, he said, and agents followed him wherever he went.

In a May 2003 incident in the Washington, D.C., neighborhood of Georgetown, Dr. Hatfill approached the car of an F.B.I. agent who had been trailing him in order to take the driver’s picture. The agent drove off and his car ran over Dr. Hatfill’s foot. Police later ticketed Dr. Hatfill for “walking to create a hazard” and he was forced to pay a fine of $5. The driver was not ticketed.

Steadfastly maintaining his innocence and declaring that his life was being destroyed by harassment, Dr. Hatfill went to court to try to clear his name.

He filed a lawsuit against the government contending that officials had leaked information about him in violation of the Privacy Act. As part of that case, the court subpoenaed reporters who had quoted anonymous law enforcement officials about his case in an attempt to force them to reveal their sources.

Earlier this year, the judge in the case, Reggie Walton, found Toni Lacy, a former reporter for USA Today, in contempt of court when she refused to reveal the sources of information in several articles about the case.

“There’s not a scintilla of evidence to suggest Dr. Hatfill had anything to do with it,” Judge Walton said at the time, yet the public notoriety has “destroyed his life.”

Ms. Lacy appealed the decision, but Dr. Hatfill’s lawyers dropped their demands for her testimony after the United States government agreed in June to pay the former Army scientist $2.825 million and an annual annuity of $150,000 to settle the lawsuit.

Dr. Hatfill also sought to clear his name by suing news outlets, saying that articles suggesting that he might have been behind the anthrax mailings had defamed him.

He sued The New York Times and one of its op-ed columnists, Nicholas D. Kristof. That lawsuit was dismissed, but Dr. Hatfill has appealed the dismissal.

The former Army scientist also sued Vanity Fair and the author of an article about the case in the magazine, Donald Foster, as well as Reader’s Digest, which had republished a version. The case was settled confidentially in 2007.

Thomas G. Connolly, an attorney for Dr. Hatfill, said on Friday that he had “nothing at this point” to say about the case. Mr. Connolly said that he would wait until the FBI released more information about its investigation of Dr. Ivins after first briefing the family members of the victims.

“Out of respect for the victims’ families, we’re not going to make any comments until the families are briefed,” Mr. Connolly said.

Dr. Hatfill, Mr. Connolly added, was not interested in speaking directly with the media about the case.

WASHINGTON — After four years pursuing one former Army scientist on a costly false trail, F.B.I. agents investigating the deadly anthrax letters of 2001 finally zeroed in last year on a different suspect: another Army scientist from the same biodefense research center at Fort Detrick in Frederick, Md.

 Over the last 18 months, even as the government battled a lawsuit filed by the first scientist, Steven J. Hatfill, investigators built a case against the second one, Bruce E. Ivins, a highly respected microbiologist who had worked for many years to design a better anthrax vaccine.

Last weekend, after learning that federal prosecutors were preparing to indict him on murder charges, Dr. Ivins, a 62-year-old father of two, took an overdose of Tylenol with codeine. He died in a Frederick hospital on Tuesday, leaving behind a grieving family and uncertainty about whether the anthrax mystery had finally been solved.

The apparent suicide of Dr. Ivins, a Red Cross volunteer and amateur juggler who had won the Defense Department’s highest civilian award in 2003, was a dramatic turn in one of the largest criminal investigations in the nation’s history. The attack, the only major act of bioterrorism on American soil, came in the jittery aftermath of the Sept. 11 attacks. It killed five people, sickened 17 others and set off a wave of panic.

In the early days after the letter attacks, in September and October 2001, Dr. Ivins joined about 90 of his colleagues at the Army Medical Research Institute of Infectious Diseases in a round-the-clock laboratory push to test thousands of samples of suspect powder to see if they were anthrax. Later, in April 2002, he came under scrutiny in an Army investigation of a leak of potentially deadly anthrax spores outside a sealed-off lab at Fort Detrick. He later admitted he had discovered the leak but not reported it.

 Whether the focus on Dr. Ivins had resolved the case of the anthrax letters was unclear. A federal law enforcement official said that Dr. Ivins had been regarded as a strong suspect and that agents had been nearing an arrest, and a lawyer familiar with the investigation said he believed that prosecutors had planned to charge only Dr. Ivins. The link between Dr. Ivins’s suicide and the federal investigation was first reported on Friday in The Los Angeles Times.

But the Federal Bureau of Investigation declined on Friday to make public its case against Dr. Ivins, noting that evidence was under court seal as part of a grand jury investigation. Officials said they were briefing the victims of the anthrax letters — those who recovered, as well as family members of those who died — and would need to go to court to have evidence unsealed before it could even be summarized for the public.

A lawyer who had represented Dr. Ivins since May 2007, Paul F. Kemp, insisted that Dr. Ivins was innocent and had been driven to suicide by false suspicions.

“For six years, Dr. Ivins fully cooperated with that investigation, assisting the government in every way that was asked of him,” Mr. Kemp said in a written statement, calling the microbiologist “a world-renowned and highly decorated scientist who served his country for over 33 years with the Department of the Army.”

“We assert his innocence in these killings and would have established that at trial,” Mr. Kemp said. “The relentless pressure of accusation and innuendo takes its toll in different ways on different people, as has already been seen in this investigation.”

Mr. Kemp was clearly referring to the case of Dr. Hatfill, who was the focus of intensive F.B.I. and news media attention in the case beginning in mid-2002 and received a $4.6 million settlement from the government in June to settle a lawsuit accusing the F.B.I. and the Justice Department of destroying his career and personal life with leaks.

Whatever the cause of his suicide, Dr. Ivins had been behaving bizarrely in the weeks before his death. He was hospitalized briefly for depression and, according to a complaint filed with the police, threatened to kill a social worker who had treated him in group therapy, among others, in rants referring to his expectation that he would be charged with five counts of capital murder. 

“It’s out of character,” said Norman M. Covert, a former spokesman and historian for the Army biodefense center who served with Dr. Ivins on an animal care committee. “But if the F.B.I. was really leaning on him, what a tremendous load that was on him.”

A spokesman for the Frederick police, Lt. Clark Pennington, said he could not say whether Dr. Ivins had left a suicide note because the anthrax investigation remained open.

Investigators in the huge inquiry traveled to many countries and by late 2006 had conducted 9,100 interviews, sent out 6,000 grand jury subpoenas and conducted 67 searches, the F.B.I. said. But the prime focus steadily narrowed: first to the Army infectious diseases laboratories, apparently linked to the letters by genetic analysis, then to Dr. Hatfill, a medical doctor who had become a bioterrorism consultant, and finally to Dr. Ivins, who worked in the same building as Dr. Hatfill and lived two blocks away from him outside the gates to Fort Detrick.

Two puzzles have haunted investigators from the beginning: the motive of the perpetrator and his skills. Because the notes in some of the letters mailed to news media organizations and two senators included radical Islamist rhetoric, investigators initially believed the letters might have been sent by Al Qaeda.

But the F.B.I. quickly settled on a different profile: a disgruntled American scientist or technician, perhaps one specializing in biodefense, who wanted to raise an alarm about the bioterrorism threat. That theory accounted for the letters’ taped seams and the notes’ use of the word anthrax, a warning that allowed antibiotic treatment — not to be expected from a Qaeda attack intended mainly to kill.

That theory of a biodefense insider placed many scientists at the infectious diseases institute and other laboratories under scrutiny, even as they helped the F.B.I. analyze the anthrax powder in the letters.

“The F.B.I. would be remiss not to look at us, especially those of us who worked with anthrax,” said John W. Ezzell, an anthrax researcher who hired Dr. Ivins at the institute and knew him well. “We were all subjected to lie detector tests. We were all interviewed.”

Mr. Ezzell called Dr. Ivins “intense about his work, but a popular guy.” Asked whether he was aware that Dr. Ivins had become a more serious suspect, Mr. Ezzell declined to comment.

The other puzzle involved the skills necessary to produce the high-quality aerosol powder contained in the letters addressed to the senators, Tom Daschle, Democrat of South Dakota, and Patrick J. Leahy, Democrat of Vermont.

Scientists familiar with germ warfare said there was no evidence that Dr. Ivins, though a vaccine expert with easy access to the most dangerous forms of anthrax, had the skills to turn the pathogen into an inhalable powder.

“I don’t think a vaccine specialist could do it,” said Dr. Alan P. Zelicoff, a physician who aided the F.B.I. investigation when he worked at the Sandia National Laboratories in Albuquerque.

“This is aerosol physics, not biology,” Dr. Zelicoff added. “There are very few people who have their feet in both camps.”

Mr. Ezzell said Dr. Ivins had worked on many projects involving anthrax spores and the toxin they produce, including experiments in which animals were exposed to anthrax to test vaccines. But he said the experiments, to his knowledge, involved anthrax spores in liquid and not in the dry powder form used in the letter attacks.

By their own admission, the F.B.I. and the Postal Inspection Service had little expertise in biological weapons in 2001, when they first loosed hundreds of agents on the investigation. Since then, at least 19 government and university laboratories have worked on the investigation, using clues like the genetic fingerprints of the anthrax, and radioactive isotopes in the water used to grow it, to try to trace it to a source.

The source, several officials said, was the infectious diseases institute, where the trail led to just a handful of vials in a single lab.

But the scientific evidence, some of it found using new methods, now may never be tested in a criminal trial, leaving questions about just how compelling it is.

“I would urge the bureau to publish its evidence if it declares the case solved and closed,” said Dr. Claire Fraser-Liggett, the former director of the Institute for Genomic Research, where the anthrax genome was decoded.

On Capitol Hill, where anthrax contamination in 2001 led to the evacuation of many offices, several members of Congress voiced skepticism about reports that the hunt for the anthrax killer might be over.

Representative Rush Holt, a Democrat whose district includes the Princeton, N.J., mailbox where investigators believe the letters were mailed, said the F.B.I. should provide a full briefing.

“What we learn,” Mr. Holt said, “will not change the fact that this has been a poorly handled investigation that has lasted six years and already has resulted in a trail of embarrassment and personal tragedy.”

William J. Broad and Nicholas Wade contributed reporting, and Jack Begg, Kitty Bennett and Barclay Walsh contributed research.

FREDERICK, Md. — Bruce E. Ivins arrived last month for a group counseling session at a psychiatric center here in his hometown with a startling announcement: Facing the prospect of murder charges, he had bought a bulletproof vest and a gun as he contemplated killing his co-workers at the nearby Army research laboratory.

“He was going to go out in a blaze of glory, that he was going to take everybody out with him,” said a social worker in a transcript of a hearing at which she sought a restraining order against Dr. Ivins after his threats.

The ranting represented the final stages of psychological decline by Dr. Ivins that ended when he took his life this week, as it became clear that he was a suspect in the 2001 anthrax attacks.

For more than three decades, Dr. Ivins, 62, had worked with some of the world’s most dangerous pathogens and viruses, trying to find cures in case they might be used as a weapon. Now he was a suspect in the nation’s worst biological attack.

To some of his longtime colleagues and neighbors, it was a startling and inexplicable turn of events for a churchgoing, family-oriented germ researcher known for his jolly disposition — the guy who did a juggling act at community events and composed satiric ballads he played on guitar or piano to departing co-workers.

“He did not seem to have any particular grudges or idiosyncrasies,” said Kenneth W. Hedlund, a retired physician who once worked alongside Dr. Ivins at the Army Medical Research Institute of Infectious Diseases in Frederick. “He was the last person you would have suspected to be involved in something like this.”

But to some anthrax experts, while reserving judgment on Dr. Ivins’s case, his identification as a suspect fit a pattern they had suspected might explain the crime: an insider wanting to draw attention to biodefense.

Dr. Ivins, the son of a pharmacist from Lebanon, Ohio, who held a doctorate in microbiology from University of Cincinnati, spent his entire career at the elite, Army-run laboratory that conducted high-security experiments into lethal substances like anthrax and Ebola.

He turned his attention to anthrax — putting aside research on Legionnaire’s disease and cholera — after the 1979 anthrax outbreak in the Soviet city of Sverdlovsk, which killed at least 64 after an accidental release at a military facility, said Dr. Hedlund, who worked with Dr. Ivins at the time.

The work became even more intense in the aftermath of the 2001 anthrax attack, as the field grew tremendously, with billions of dollars in new federal support for research on anthrax and other potential biological weapons and to buy new drugs or vaccines to handle a possible future attack.

Dr. Ivins was among the scientists who benefited from this surge, as 14 of the 15 academic papers he published since late 2001 were focused on possible anthrax treatments or vaccines, comparing the effectiveness of different formulations. He even worked on the investigation of the anthrax attacks, although this meant that he, like other scientists at the Army’s defensive biological laboratory at Fort Detrick, Md., was scrutinized as a possible suspect.

Dr. Ivins and his wife, Diane Ivins, raised two children in a modest Cape Cod home in a post-World War II neighborhood right outside Fort Detrick, and he could walk to work.

He was active in the community, volunteering with the Red Cross and serving as the musician at his Roman Catholic church. His showed off his music skills at work, too, playing songs he had written about friends who were moving to new jobs.

But as investigators intensified their focus on Dr. Ivins, his life began to come apart.

Local police records show unusual calls this past spring, including the report of an “unconscious male” in March. For at least six months of this year, he had attended group counseling sessions at a psychiatric center and had apparently been seeing a psychiatrist.

W. Russell Byrne, a former colleague of Dr. Ivins at the biodefense laboratory, criticized federal agents as harassing the germ scientist and his family.

“They searched his house twice and his computer once,” he said in an interview. “We all felt powerless to stop it.”

He said Dr. Ivins was recently escorted away from the laboratory by the authorities and “disgraced in a place he spent his whole career.”

“That was so humiliating,” he said. “It’s hard to believe.”

In court records, filed after Dr. Ivins discussed his plans to kill his co-workers, a social worker who led the sessions, Jean Duley, said that Dr. Ivins’s psychiatrist had “called him homicidal, sociopathic with clear intentions.” She went on to say that the Federal Bureau of Investigation was looking at Dr. Ivins and that he would soon be charged with five murders — the same number of fatalities in the anthrax attacks.

“He is a revenge killer,” Ms. Duley told a Maryland District Court judge in Frederick as she sought a restraining order against Dr. Ivins. “When he feels that he has been slighted, and especially towards women, he plots and actually tries to carry out revenge killings.”

After Dr. Ivins made the threats on July 9 about killing his co-workers, he was detained while at work and taken to a hospital before being transferred to a nearby psychiatric hospital. He was later released, but forbidden from going to Fort Detrick.

Ms. Duley said that Dr. Ivins had a history of making homicidal threats that dated to his college days. But several of Dr. Ivins’s co-workers said that while he clearly was devastated after he was singled out for possible prosecution, that does not mean he was involved in the attack.

The police had come to Dr. Ivins’s home in response to a call early on July 27 from the fire department for assistance; they found him unconscious on the bathroom floor. He was transported to the hospital, and died two days later.

His family has made no public statement about the investigation or about Dr. Ivins’s suicide. But his children both placed messages on their Facebook pages, saying goodbye to their father, hinting at the torment he went through in his final months.

“I will miss you Dad. I love you and I can’t wait to see you in Heaven,” his son, Andy Ivins, wrote. “Rest in peace. It’s finally over.”

Sarah Abruzzese reported from Frederick, and Eric Lipton from Washington. William J. Broad contributed reporting from New York.

WASHINGTON — Until the anthrax attacks of 2001, Bruce E. Ivins was one of just a few dozen American bioterrorism researchers working with the most lethal biological pathogens, almost all at high-security military laboratories.

Today, there are hundreds of such researchers in scores of laboratories at universities and other institutions around the United States, preparing for the next bioattack.

But the revelation that F.B.I. investigators believe that the anthrax attacks were carried out by Dr. Ivins, an Army biodefense scientist who committed suicide last week after he learned that he was about to be indicted for murder, has already re-ignited a debate: Has the unprecedented boom in biodefense research made the country less secure by multiplying the places and people with access to dangerous germs?

“We are putting America at more risk, not less risk,” said Representative Bart Stupak, Democrat of Michigan and chairman of a House panel that has investigated recent safety lapses at biolabs.

F.B.I. investigators have long speculated that the motive for the attacks, if carried out by a biodefense insider like Dr. Ivins, might have been to draw public attention to a dire threat, attracting money and prestige to a once-obscure field.

If that was the motive, it succeeded. In the years since anthrax-laced letters were sent to members of Congress and news organizations in late 2001, almost $50 billion in federal money has been spent to build new laboratories, develop vaccines and stockpile drugs. For example, an experimental vaccine Dr. Ivins had spent years working on moved from the laboratory to a proposed billion-dollar federal contract after the attacks, which killed five people.

Dr. Ivins helped invent an anthrax vaccine that was slated to be added to the nation’s vaccine stockpile through an $877 million contract awarded in 2004, but the deal collapsed two years later.

Despite the insistence of Dr. Ivins’s lawyer and some of the scientist’s colleagues that he was innocent, officials at the Justice Department and the Federal Bureau of Investigation on Saturday appeared confident that they had the right man, though they said they were still weighing how and when to seek an end to the grand jury investigation.

“That’s not a decision we’re going to make lightly,” one Justice Department official said Saturday. “There won’t be a rush to judgment.”

Dr. Ivins’s lawyer, Paul F. Kemp, said by e-mail on Saturday that news reports that his client was considering a plea bargain were “entirely spurious.”

Nearly seven years have passed without another biological attack, which has reduced the sense of urgency about the bioterrorist threat, even among some specialists.

“I think it’s an important risk, but frankly I’m more concerned about bombs and guns, which are easily available and can be very destructive,” said Randall S. Murch, a former F.B.I. scientist who has studied ways to trace a bioterrorist attack to its source.

Federal officials say they are convinced that the increase in spending has brought real gains.

“Across the spectrum of bio-threats we have expanded our capacity significantly,” said Craig Vanderwagen, an assistant secretary at the Department of Health and Human Services who oversees the biodefense effort. Systems to detect an attack, investigate it and respond with drugs, vaccines and cleanup are all hugely improved, Mr. Vanderwagen said. “We can get pills in the mouth,” he said.

Supporters of the spending increase cite studies that project apocalyptic tolls from a large-scale biological attack. One 2003 study led by a Stanford scholar, for instance, found that just two pounds of anthrax spores dropped over an American city could kill more than 100,000 people, even if antibiotic distribution began quickly.

And there is ample evidence that Qaeda leaders have shown interest in using biological weapons. Yazid Sufaat, a Malaysian-born Qaeda biochemist who trained in the United States, spent several months in 2001 trying to cultivate anthrax in Kandahar, Afghanistan.

But the proliferation of biodefense research laboratories presents real threats, too, Congressional investigators recently warned.

More people in more places handling toxic agents create more opportunities for an accident or intentional misuse by an insider, Keith Rhodes, an investigator with the Government Accountability Office, said at a Congressional hearing in October.

“The Federal Bureau of Investigation and the intelligence community were the ones who were most concerned about it,” Mr. Rhodes testified.

Nationwide, there are an estimated 14,000 people working at about 400 laboratories who have permission to work with so-called “select agents” — which could be used in a bioterror attack — although a much smaller amount of this research involves the most dangerous materials, like anthrax.

With so many people involved, there is insufficient federal oversight of biodefense facilities to make sure the laboratories follow security rules and report accidents that might threaten lab workers or, in an extreme case, lead to a release that might endanger the public, Mr. Rhodes testified.

In effect, the government may be providing the tools that a would-be terrorist could use, said Richard H. Ebright, a Rutgers University biochemist and vocal critic of the federal increase in biodefense spending.

“One well-placed student, technician or senior scientist — no cost, with the salary being provided courtesy of the U.S. taxpayer — and no risk, no difficulty,” Mr. Ebright said. “That is all it takes.”

Heightening the concern has been a string of accidents at certain new or expanded biodefense laboratories, several of which were not properly reported to the authorities when they first took place.

One of the first accidents was in Dr. Ivins’s lab in late 2001, when he and his colleagues were aiding the federal investigation of the anthrax attacks and spores accidentally spilled outside the secure area.

Dr. Ivins failed to report the event to his superiors and instead tried to disinfect the contaminated areas, according to an Army report, which concluded, “Adherence to institute safety procedures by laboratory personnel is lax.”

In early 2006, at Texas A&M University, a worker was infected with Brucella bacteria, a pathogen common in livestock that can cause flulike symptoms like fever, fatigue and joint pain, although it is rarely fatal. Later, three researchers at the same lab were infected with Q fever, another cattle-borne disease that can cause serious but generally not fatal illness in humans.

After the two incidents belatedly became public, federal officials temporarily shut down the laboratory, citing a series of safety shortcomings, such as unapproved experiments and staff given access to the dangerous agents even though they had not been approved to handle them.

Apart from the threat from insiders, some public health experts believe money being used to study obscure pathogens that are not a major disease problem could be better directed to study known killers like influenza or AIDS.

Partly in response to this criticism, government officials now often talk about how strengthening the systems necessary to respond to a terror attack would also prepare the country for a natural epidemic like avian flu.

As experts debate threats, nervous neighbors of expanding biodefense facilities have repeatedly rallied to try to defeat them. At Fort Detrick, where Dr. Ivins worked, some residents have opposed the construction of a “national biodefense campus” slated to include a new building to house the United States Army Medical Research Institute of Infectious Diseases, where Mr. Ivins worked for many years before his suicide. Three other new labs on the campus will be operated by the Departments of Homeland Security, Health and Human Services, and Agriculture.

Proponents say that clustering the laboratories on a military base will encourage safe scientific collaboration and save money through sharing of some facilities.

The build-up, and the related increase in research, has brought some important advances, federal officials argue, like a promising new experimental vaccines or therapies to treat smallpox or Ebola virus.

The country now also has a greatly expanded stockpile of vaccines and drugs to treat anyone exposed in a future attack, including enough antibiotics to treat more than 40 million Americans who might be exposed to anthrax and nearly 5 million bottles of a special potassium iodide liquid that help protect infants from harm caused by nuclear fallout.

The deal for the $877 million contract that included Dr. Ivins’s vaccine collapsed in 2006 after the contractor, VaxGen of Brisbane, Calif., failed to meet deadlines. VaxGen, in a licensing agreement with the Army to produce the vaccine, had listed two patents held by Dr. Ivins and his colleague, but it made no mention of compensation planned for their work. Dr. Ivins’s patents were first reported by The Los Angeles Times.

Arthur Friedlander, one of Dr. Ivins’s collaborators in the work that led to the anthrax vaccine patent in 2002, declined to comment when asked Saturday if he and others who had worked on the project stood to gain financially. He referred the question to an Army spokeswoman, who did not respond to a request for comment. Mr. Kemp, Dr. Ivins’s lawyer, said he could not comment on the notion that Dr. Ivins stood to earn royalties from vaccine patents because of attorney-client privilege.

VaxGen had agreed to pay royalties to the Army in exchange for the license to produce the new anthrax vaccine, according to federal financial disclosure it filed. And Army policy would allow the inventor to receive up to $150,000 a year “of any royalties/payments resulting from commercial licensure.”

It is unclear what the specific deal in this case might have been, or how the royalties might have been split among the five researchers whose names were on the patent.

Michael Greenberger, director of the Center for Health and Homeland Security at the University of Maryland, said he was convinced that the increased spending had left the nation better prepared for a future attack, without creating significant new vulnerabilities.

“You can never say that the system is 100 percent secure,” he said. “But the research ethic today is one of much greater disciple and focus on security than was true prior to the anthrax attacks.”

Representative Stupak, though, remains concerned.

“You have all these universities tripping over each other trying to be high-level biosecurity labs,” he said. “What the nation gets is a very expensive bill, less security and a greater risk to the surrounding communities.”

Eric Lichtblau and William J. Broad contributed reporting.

The evidence amassed by F.B.I. investigators against Dr. Bruce E. Ivins, the Army scientist who killed himself last week after learning that he was likely to be charged in the anthrax letter attacks of 2001, was largely circumstantial, and a grand jury in Washington was planning to hear several more weeks of testimony before issuing an indictment, a person who has been briefed on the investigation said on Sunday.

While genetic analysis had linked the anthrax letters to a supply of the deadly bacterium in Dr. Ivins’s laboratory at Fort Detrick, Md., at least 10 people had access to the flask containing that anthrax, said the source, who spoke on condition of anonymity because he was not authorized to discuss the investigation publicly.

Agents from the Federal Bureau of Investigation also have no evidence proving that Dr. Ivins visited New Jersey on the dates in September and October 2001 when investigators believe the letters were sent from a Princeton mailbox, the source said.

The source acknowledged that there might be some elements of the evidence of which he was unaware. And while he characterized what he did know about as “damning,” he said that instead of irrefutable proof, investigators had an array of indirect evidence that they argue strongly implicates Dr. Ivins in the attacks, which killed 5 people and sickened 17 others.

That evidence includes tracing the prestamped envelopes used in the attacks to stock sold in three Maryland post offices, including one in Frederick, frequented by Dr. Ivins, who had long rented a post office box there under an assumed name, the source said. The evidence also includes records of the scientist’s extensive after-hours use of his lab at the United States Army Medical Research Institute of Infectious Diseases around the time the letters were mailed, the source said.

In an indication that investigators were still trying to strengthen their case, F.B.I. agents took two public computers from the downtown public library in Frederick last week, The Frederick News-Post reported.

One law enforcement official said on Sunday that evidence against Dr. Ivins might be made public as early as Wednesday, if the bureau could persuade a federal judge to unseal the evidence and if agents could brief survivors of the anthrax attacks and family members of those who died.

Paul F. Kemp, a lawyer for Dr. Ivins who maintains his client’s innocence, declined to comment for the record on Sunday on the alleged evidence.

The stakes for the beleaguered F.B.I. and its troubled investigation, now in its seventh year, could hardly be higher.

The bureau, having recently paid off one wrongly singled-out researcher, Dr. Steven J. Hatfill, now stands accused by Dr. Ivins’s lawyer and some of his colleagues of hounding an innocent man to suicide. Only by making public a powerful case that Dr. Ivins was behind the letters can the F.B.I. begin to redeem itself, members of Congress say and some bureau officials admit privately.

Tom Daschle of South Dakota, the former Democratic leader of the Senate and one target of the deadly letters, said on Sunday that he had long had grave doubts about the investigation.

“From the very beginning, I’ve had real concerns about the quality of the investigation,” Mr. Daschle said on Fox News Sunday.

“Given the fact that they already paid somebody else $5 million for the mistakes they must have made gives you some indication of the overall caliber and quality of the investigation,” Mr. Daschle added. He was referring to the government’s settlement in June with Dr. Hatfill, which pays him $2.825 million plus $150,000 a year for life to compensate him for what the F.B.I. now acknowledges was a devastating focus for years on the wrong man.

Mr. Daschle said he did not know whether the new focus on Dr. Ivins was “just another false track.” He added, “We don’t know, and they aren’t telling us.”

John Miller, an F.B.I. assistant director, declined on Sunday to address criticism of the investigation, one of the largest and most costly in bureau history.

“As soon as the legal constraints barring disclosure are removed, we will make public as much information as possible,” Mr. Miller said in a statement. “We will do that at one time, in one place. We will do that after those who were injured and the families of those who died are briefed, which is only appropriate.”

He added, “I don’t believe it will be helpful to respond piecemeal to any judgments made by anyone before they know a fuller set of facts.”

The unsealed evidence would likely include affidavits for search warrants laying out the bureau’s reasons for focusing on Dr. Ivins, including summaries of scientific evidence that investigators consider central to their case. Dr. Ivins’s house near the gates to Fort Detrick was the subject of an extensive search by F.B.I. agents last Nov. 1, and bureau surveillance vehicles openly followed the scientist for about a year, according to people who knew him.

Dr. Ivins, 62, had acted strangely in the weeks before his death, and he was hospitalized from about July 10 to July 23 after associates concluded that he might be a danger to himself or others. Jean C. Duley, a social worker who had treated him in group therapy, sought a restraining order against him. He had said he expected to be charged with “five capital murders,” she said, and had threatened to kill colleagues and himself.

Ms. Duley did not say that Dr. Ivins had confessed to the anthrax attacks, and the scientist left no suicide note, according to an official briefed on the investigation.

Critics say the Hatfill settlement was the culmination of a pattern of blunders in the investigation. The F.B.I. and the United States Postal Inspection Service have thrown a huge amount of resources into the hunt for the anthrax mailer, whose letters dislodged members of Congress and Supreme Court justices from contaminated buildings, which cost hundreds of millions of dollars to clean up.

Yet from the beginning, public glimpses of the investigators’ work prompted serious questions. “What has bothered me is the unscientific, bumbling approach of our investigators,” said Representative Rush D. Holt, a Democrat and physicist whose New Jersey district includes the contaminated Princeton mailbox.

Mr. Holt said in a recent interview that his first doubts came after anthrax was found in his Congressional office in October 2001 but investigators never returned to conduct systematic testing to trace the path of the anthrax spores.

After that, he said, when contamination at a New Jersey postal processing center indicated that the letters had been mailed on one of a limited number of routes, it took investigators seven months to test several hundred mailboxes and identify the source.

“Within two days they could have dispatched 50 people to wipe all those mailboxes,” Mr. Holt said. He wrote to Robert S. Mueller III, the F.B.I. director, on Friday to ask that he testify to Congress about the investigation as soon as it is closed.

When investigators questioned people around the Princeton mailbox about whether they had seen a suspect there, they showed passers-by photos of only Dr. Hatfill, according to local residents who were questioned. Criminologists said that only by showing photos of a number of people could investigators have confidence in an eyewitness identification of Dr. Hatfill or any other suspect.

Some experts also questioned the F.B.I.’s use of bloodhounds from local police departments to try to trace a scent from the recovered letters to suspects’ homes, including that of Dr. Hatfill.

Law enforcement sources at the time said the bloodhounds’ reactions at Dr. Hatfill’s apartment were one reason for the F.B.I.’s intense focus on him. But independent bloodhound handlers said it was highly unlikely that a useful scent could be obtained from letters that might have been handled by the perpetrator with gloves, had rubbed against thousands of other scents in the mail and then were irradiated to kill the dangerous spores.

WASHINGTON — After four years of painstaking scientific research, the F.B.I. by 2005 had traced the anthrax in the poisoned letters of 2001 to a single flask of the bacteria at the Army biodefense laboratory at Fort Detrick, Md., according to government scientists and bureau officials.

But at least 10 scientists had regular access to the laboratory and its anthrax stock — and possibly quite a few more, counting visitors from other institutions, and workers at laboratories in Ohio and New Mexico that had received anthrax samples from the flask at the Army laboratory.

To get that far, the Federal Bureau of Investigation had helped invent what was virtually a new science, microbial forensics, the use of biochemical clues to track a germ weapon to its source.

The bureau sponsored research at a score of government and university laboratories intended to estimate the age of the anthrax, tracing the water used to grow it, assessing how it was made into an inhalable powder and, perhaps most important, taking its genetic fingerprint.

But at that point, the science had largely reached its limits. To figure out who in the narrowed pool of scientist-suspects was the perpetrator, the F.B.I. would have to rely on traditional gumshoe investigative methods: interviewing colleagues and family members, searching houses and cars, doing surveillance, and assessing personalities.

About 18 months ago, investigators appeared to sharpen their focus on Bruce E. Ivins, a veteran anthrax researcher, whom they placed under intensive surveillance as they examined every aspect of his life and work.

Since Dr. Ivins’s suicide last week, F.B.I. officials have said prosecutors were preparing to indict him for sending the anthrax letters, which killed five people, although charges appear to have been a few weeks away.

Dr. Ivins had been a respected microbiologist for three decades at the United States Medical Research Institute of Infectious Diseases at Fort Detrick. He was a popular neighbor in Frederick, Md., a Red Cross volunteer and an amateur juggler who played keyboards at his church.

But the investigators found some personal quirks, according to law enforcement officials and people who knew the scientist well. They found that Dr. Ivins, who had a history of alcohol abuse, had for years maintained a post office box under an assumed name that he used to receive pornographic pictures of blindfolded women.

Years ago, he had visited Kappa Kappa Gamma sorority houses at universities in Maryland, Virginia and West Virginia, an obsession growing out of a romance with a sorority sister in his own college days at the University of Cincinnati — although someone who knew him well said the last such visit was in 1981.

What is more relevant, agents focused new attention on a 2002 Army investigation of a spill of anthrax the same year outside the secure laboratory that Dr. Ivins worked in, and his puzzling behavior in trying to clean the area with bleach while failing to report the contamination. They studied his anthrax vaccine patents and considered whether the promise of royalties after a bioterrorism scare might have been a motive. They noted that he had a lyophilizer, which could be used to dry wet anthrax into powder, a form not ordinarily used at Fort Detrick.

They had even intensively questioned his adopted children, Andrew and Amanda, now both 24, with the authorities telling his son that he might be able to collect the $2.5 million reward for solving the case and buy a sports car, and showing his daughter gruesome photographs of victims of the anthrax letters and telling her, “Your father did this,” according to the account Dr. Ivins gave a close friend.

As the investigation wore on, some colleagues thought the F.B.I.’s methods were increasingly coercive, as the agency tried to turn Army scientists against one another and reinterviewed family members.

One former colleague, Dr. W. Russell Byrne, said the agents pressed Dr. Ivins’s daughter repeatedly to acknowledge that her father was involved in the attacks.

“It was not an interview,” Dr. Byrne said. “It was a frank attempt at intimidation.”

Dr. Byrne said he believed Dr. Ivins was singled out partly because of his personal weaknesses. “They figured he was the weakest link,” Dr. Byrne said. “If they had real evidence on him, why did they not just arrest him?”

Another former co-worker, Dr. Kenneth W. Hedlund, who collaborated on anthrax research with Dr. Ivins in the 1980s, had a similar theory.

“The investigators looked around, they decided they had to find somebody. They went after all of them but he looked the most susceptible to pressure,” Dr. Hedlund said. “It is like prisoners of war: if they are harassed enough, they will be driven to do anything. But I don’t believe he would have done what they say he did.”

With such views voiced by Dr. Ivins’s acquaintances — and vocal skepticism from key members of Congress — the pressure is growing on the F.B.I. to unveil its evidence.

On Monday, officials began to contact survivors of the anthrax attacks and family members of the five who died to say they would get a briefing, in person or by telephone, before the case against Dr. Ivins was made public.

Shirley Davis, the primary caretaker for Ottilie W. Lundgren of Oxford, Conn., a 94-year-old woman who was killed in the anthrax letter attack, said that she received a call on Monday.

“They asked if we could put together a list of questions we would like to have answered, just to get an idea of just exactly what happened,” Ms. Davis, 78, said. She said she had not yet been given a day or time for the briefing.

“It is a relief to know that they have found something,” Ms. Davis said. “It has been seven years now. But it may end up still that they don’t really know why this happened or what happened.”

F.B.I. officials say they do know a great deal about what happened and will make it public, possibly as early as Wednesday. They say the core of their case will be the science, which produced the giant step from a globe of possible suspects to a single lab and a single flask.

Faced with the scientific mystery of the powder, government and outside scientists first looked at chemical isotopes in the attack strain for clues as to when and where the bacteria had been grown. Analyzing traces of the beef broth used to grow the anthrax, scientists measured carbon-14 left from nuclear weapons tests in the 1950s, whose quantity diminishes every year.

By calculating the ratio of carbon-14 to the normal kind in residue of plants eaten by the cow from which the broth was made, investigators learned by June 2002 that the anthrax had been grown within the last two years.

A second clue was developed from the new ability to sequence, or decode, the chemical letters of DNA. Scientists at the Institute for Genomic Research, a pioneer in genome sequencing, sequenced the full genome of the anthrax recovered from the blood of Robert Stevens, the first victim of the attacks.

The genome of various stocks of the Ames strain of anthrax used in the attacks were almost identical in all the 5 million chemical letters of their DNA. But researchers found enough differences in the attack strain to provide a reasonable chance of identifying its source.

The chief difference was that a stretch of DNA was flipped head to tail in some bacteria in the attack strain, but not in any other samples.

Further, the attack strain contained bacteria with both the flipped and the unflipped DNA, showing that it was a mixture of two strains, which analysts later found reflected a mix of origins — 85 percent from the Dugway Proving Ground of the Army in Utah and 15 percent added at Fort Detrick, according to one person close to the investigation.

To make sure the case for the distinctive features of the attack anthrax could hold up in court, agents collected thousands of samples of Ames strain anthrax from labs around the world, said scientists familiar with the F.B.I.’s thinking. “This is the step that took so long,” one scientist said.

Decoding the genome of a bacterium like anthrax may have cost around $500,000 in 2002, and even the F.B.I.’s budget would have been strained to decode thousands of genomes. A new generation of sequencing machines can now sequence bacterial genomes for around $500. But those machines did not become available until about 2005, which may have been another reason for the delay.

Despite speculation that the anthrax had a special coating to make it more deadly, an F.B.I. scientist, Douglas Beecher, published an article in 2006 saying no such sophisticated additives had been found. That finding broadened the number of scientists and technicians who could have made the anthrax, another obstacle to a quick resolution.

Richard Ebright, a Rutgers University biochemist and an opponent of the rapid expansion of biodefense research since 2001, said the F.B.I. should long ago have released some of its scientific conclusions.

“The finding that the attack material could be traced definitively to a U.S. bioweapons research lab could, and should, have been released as soon is it was obtained,” Dr. Ebright said, noting that the finding could raise questions about the wisdom of proliferating stocks of anthrax and other pathogens.

“This is not just a finding with Agatha Christie-Perry Mason implications,” he said.

Scott Shane reported from Washington, and Nicholas Wade from New York. Eric Lipton, Eric Lichtblau and Sarah Abruzzese contributed reporting from Washington.

WASHINGTON — In the face of growing questions about the strength of the evidence, the Justice Department is preparing to declare the 2001 anthrax case solved and to make its case publicly on Wednesday against a military scientist who killed himself after investigators linked him to the attacks, federal law enforcement officials said Tuesday.

Officials at the Federal Bureau of Investigation are particularly eager to close the case and publicly rebut accusations from defenders of the scientist, Bruce E. Ivins, that the bureau may have hounded an innocent man into committing suicide.

But the legal process for effectively closing the case — and unsealing court records that are secret under grand jury rules — has proved to be a slow one. Justice Department officials plan to ask Chief Judge Royce C. Lamberth of Federal District Court for the District of Columbia to make documents from the investigation public, but they first want to brief relatives of many of the 5 people killed and 17 injured in the anthrax attacks.

Attorney General Michael B. Mukasey said Tuesday that the authorities had a “legal and moral obligation” to speak with the victims’ families before releasing information publicly. The Justice Department plans to brief the families and release the documents on Wednesday, although no announcement has been scheduled, Mr. Mukasey and other officials said.

Three victims said the Justice Department alerted them on Tuesday to a briefing for the families in Washington on Wednesday.

Patrick D. O’Donnell, who worked as a magazine sorter in New Jersey when he was sickened by the anthrax, was on his way to Washington on Tuesday to attend the gathering. Mr. O’Donnell seemed confident, based on the news he has heard, that the F.B.I. had solved the case.

“It has taken a long time,” he said. “I guess they sat on these people long enough that they broke them. It is hard to believe it is almost over.”

Officials said Robert S. Mueller III, the F.B.I. director, might speak to some of the victims — a reflection of the importance the bureau attaches to the seven-year-old case. Members of Congress have demanded that Mr. Mueller explain why the case remained unsolved for so long. In June, the Justice Department agreed to pay a settlement worth $4.6 million to another scientist, Steven J. Hatfill, after publicly pursuing him as a suspect for years.

Law enforcement officials would not discuss many details of the investigation despite intense news media interest from around the world.

“What we have seen over the past few days has been a mix of improper disclosures of partial information mixed with inaccurate information and then drawn into unfounded conclusions,” said Brian Roehrkasse, a spokesman for the Justice Department. “None of that serves the victims, their families or the public. Likewise, we will not discuss reports or details on the timing of briefings to the public or victims and their families. We will provide such details to the press at the appropriate time, and not before.”

Dr. Ivins, who worked on anthrax vaccines for 18 years at the military research facility at Fort Detrick in Frederick, Md., took a fatal overdose of Tylenol and codeine last week at his home near the base. He had been under investigation for more than a year in the anthrax killings and had recently been told that the Justice Department was on the verge of seeking an indictment against him on capital murder charges.

Federal officials, speaking on the condition of anonymity because the case remains under seal, said they were confident that Dr. Ivins was the anthrax killer and that he had acted alone. They said that new scientific methods had allowed the F.B.I. to trace the genetic makeup of the anthrax sample to Dr. Ivins and a pool of about 10 other people who had access to a particular supply of anthrax at Fort Detrick. Other evidence, much of it still undisclosed, amounted to a strong circumstantial case against him, the officials said. Perhaps the most provocative piece of evidence to emerge publicly is the testimony of a therapist who treated Dr. Ivins in recent months and described him as homicidal.

But Dr. Ivins’s lawyer has asserted his innocence, and a number of colleagues at Fort Detrick have defended him, saying that his recent mental state and his suicide were the result of many months of near-constant surveillance and scrutiny by the F.B.I., not a reflection of his guilt.

Some government officials have also questioned the strength of the bureau’s case and said they were eager to see the grand jury documents.

One Congressional official briefed on the case said he was not persuaded that the F.B.I. had made a credible case in singling out Dr. Ivins in the group of people at Fort Detrick who had access to anthrax samples linked to the 2001 attacks.

The F.B.I. may be able to point to odd behavior on the part of Dr. Ivins, said the official, who spoke on condition of anonymity because the case is under seal. But he said the attention the bureau focused on Dr. Ivins was reminiscent of a past misstep: “It looks like what they did to Hatfill. Ivins was the weirdest one.”

Friends and colleagues, meanwhile, have offered a fuller account of Dr. Ivins’s difficult last nine months, saying that he was so distraught by the F.B.I.’s constant scrutiny that he began drinking excessively and had to be hospitalized twice for periods of weeks for substance abuse.

A friend and fellow member of a 12-step program for alcoholics who spent hours counseling him said Dr. Ivins, who at least in recent years had not been a drinker, went rapidly downhill after the F.B.I. searched his house and questioned his wife and children last November.

The friend, a fellow scientist who spoke on the condition that he not be named, said Dr. Ivins had repeatedly denied sending the anthrax letters and was particularly upset at what he considered to be the F.B.I.’s aggressive questioning of his children, Andrew and Amanda, both 24, as investigators tried to get them to turn on their father.

“He said, ‘I’m innocent of these charges,’ ” the friend said. “He was absolutely shocked they were going after him like this.” Through much of the year, the friend said, Dr. Ivins was drinking large amounts of vodka, combined with Ambien and prescription tranquilizers. After being found unconscious in his home in March, he spent four weeks in a treatment program at Suburban Hospital in Bethesda, Md. After that he spent another four weeks in treatment at the Thomas B. Finan Center in Cumberland, Md., being released to go home to Frederick in late May.

Judging from periodic phone calls in which Dr. Ivins often appeared to be intoxicated, the friend said he believed Dr. Ivins was drinking again between May and July, when he was admitted for two weeks to a psychiatric facility.

Law enforcement officials said they were confident that the F.B.I. had handled the investigation appropriately and had used proper procedures in questioning witnesses and keeping Dr. Ivins under surveillance.

Eric Lipton contributed reporting.

WASHINGTON — The Federal Bureau of Investigation on Wednesday outlined a pattern of bizarre and deceptive conduct by Bruce E. Ivins, an Army microbiologist who killed himself last week, presenting a sweeping but circumstantial case that he was solely responsible for mailing the deadly anthrax letters that killed five people in 2001.

After nearly seven years of a troubled investigation, officials of the F.B.I. and the Justice Department declared that the case had been solved. Jeffrey A. Taylor, the United States attorney for the District of Columbia, said the authorities believed “that based on the evidence we had collected, we could prove his guilt to a jury beyond a reasonable doubt.”

Some survivors of the attacks and members of Congress said they were persuaded by the evidence against Dr. Ivins, laid out in hundreds of pages of applications for search warrants unsealed for the first time. But some independent scientists, friends and colleagues of Dr. Ivins remained skeptical, noting that officials admitted that more than 100 people had access to the supply of anthrax that matched the powder in the letters.

Lawyers for Dr. Ivins reasserted their late client’s innocence and criticized the government for presenting what they called “heaps of innuendo” that failed to link him directly to the crime and would never have to be tested in court. “It was an explanation of why Bruce Ivins was a suspect,” said Paul F. Kemp, who represented the scientist for more than a year before his death on July 29 at age 62. “But there’s a total absence of proof that he committed this crime.”

The conflicting views of Dr. Ivins emerged in a day of emotional crosscurrents. At a morning memorial service at Fort Detrick in Frederick, Md., weeping Army scientists praised Dr. Ivins as a beloved colleague “known for his patience and enthusiasm for science,” as a written program put it. At the same time, at F.B.I. headquarters in Washington, the F.B.I. director, Robert S. Mueller III, and bureau officials were explaining to survivors of the anthrax attacks and relatives of the five people who died why they believe Dr. Ivins was a mass murderer.

Later, at an afternoon news conference, Mr. Taylor, the United States attorney, called Dr. Ivins “a troubled individual” who had carried out “the worst act of bioterrorism in U.S. history.”

Pressure on the F.B.I. to present a powerful case was enormous, in part because some colleagues of Dr. Ivins have accused investigators of hounding an innocent man to suicide. The skepticism was all the greater because investigators have recently acknowledged that for years they had focused on the wrong man, Steven J. Hatfill, whose career was ruined and who received a settlement worth $4.6 million from the Justice Department in June.

Justice Department officials did not give Dr. Hatfill the all-out exoneration that he and his lawyers had sought, and they appeared reluctant to even mention Dr. Hatfill by name when asked repeatedly about his status. “With respect to the individual you mentioned,” Mr. Taylor told a reporter, “we were able to determine that at no time could that individual be put in the presence of that flask from which these spores came.” Mr. Hatfill’s lawyer declined to comment.

The case against Dr. Ivins combined scientific analysis of the mailed anthrax, whose genetic fingerprint investigators linked to a supply in the scientist’s laboratory, with a review of his e-mail messages, which showed fury and frustration at problems in his anthrax vaccine research, worsening symptoms of mental illness and language that echoed a phrase in the note sent in the poisoned letters.

In addition, investigators from the F.B.I. and the Postal Inspection Service found records showing that Dr. Ivins had worked late at night in his laboratory at Fort Detrick in the days before the two mailings in September and October 2001, an unusual pattern that investigators said he did not persuasively explain.

Dr. Ivins “could provide no legitimate reason for the extended hours, other than ‘home was not good’ and he went there ‘to escape’ from his life at home,” an investigator wrote in an affidavit last Oct. 31 to persuade a judge to permit a search of his house in Frederick. Investigators also noted that envelopes used in the attacks all had a printing defect indicating that they were sold at only a small number of post offices in Maryland and Virginia in 2001 — including the location in Frederick where Dr. Ivins maintained a box under an assumed name.

An inventory of items taken in the Nov. 1 search included a briefcase containing three handguns and a “notebook detailing firearms training.”

But Mr. Kemp and his co-counsel, Thomas M. DeGonia, both of the Venable law firm, said that more important was what was not found.

Multiple searches of Dr. Ivins’s house and cars turned up not a spore of anthrax, the lawyers said, and perusal of thousands of his e-mail messages turned up no indication that he planned to commit the crime or pleasure or regret at having committed it.

Moreover, months of work uncovered no evidence that Dr. Ivins had traveled to Princeton, N.J., where investigators believe the letters were mailed. The closest connection was that a chapter house of Kappa Kappa Gamma, a sorority with which Dr. Ivins had a long and strange obsession, is located near the contaminated Princeton mailbox.

In fact, many of the documents enumerate bizarre acts and e-mail messages, many related to the sorority, with no direct relation to the anthrax case. For example Dr. Ivins engaged in an editing war on the Wikipedia entry for the Kappa Kappa Gamma sorority, trying, often unsuccessfully, “to post derogatory information.”

He wrote scores of letters to members of Congress and the news media, sometimes under assumed names, the documents said. Investigators wrote that the mailings were “significant since all of the anthrax-laden letters were sent to” media organizations and Congress.

The anthrax investigation began in October 2001 with hundreds of agents working around the clock and many expecting the letters to be linked to Al Qaeda. But investigators concluded early on that a more likely perpetrator was an American biodefense insider, possibly one who wanted to raise public awareness of the bioterrorist threat.

That was the approach when the bureau focused on Dr. Hatfill with heavily publicized searches, obvious surveillance and leaks about bloodhounds that “went crazy” in supposedly linking him to the letters. But he was not charged, and by 2003, at least some investigators doubted he was the culprit, although others continued to describe him as a suspect.

By 2005, genetic research had tied the anthrax to a supply in Dr. Ivins’s laboratory. But officials indicated that it took nearly four years to eliminate others who had access to the same supply.

At the news conference, Mr. Taylor acknowledged that the case was circumstantial but said, “We have a flask that’s effectively the murder weapon from which those spores were taken that was controlled by Dr. Ivins.”

Mr. Kemp, the defense lawyer, said the flask was far from “controlled” by Dr. Ivins. “Other scientists helped him create that anthrax and worked with it constantly,” he said. “They kept no records of who took a sample.”

Patrick D. O’Donnell, a New Jersey mail sorter who developed a severe cutaneous anthrax infection on his neck after handling a letter, attended the F.B.I. briefing, which he said drew about 40 victims and survivors, and found it compelling.

“It is hard not to be convinced, with what they have,” Mr. O’Donnell said after the meeting. “It is mostly all circumstantial. But they just have so much evidence I just can’t see it being anybody else.”

Representative Rush Holt, Democrat of New Jersey, who has been one of the F.B.I.’s most dogged critics on the case, said he found the evidence against Dr. Ivins “compelling” but wanted to know why investigators had remained focused on Dr. Hatfill for so long and why they are so certain that Dr. Ivins acted alone.

Two bioterrorism experts who reviewed the F.B.I. evidence at the request of The New York Times said the bureau would have to release far more scientific evidence to convince specialists.

One expert, Dr. Thomas V. Inglesby, deputy director of the Center for Biosecurity of the University of Pittsburgh Medical Center, said the bureau “certainly has strong circumstantial evidence” but added that “it’s important that the F.B.I. go on to release the scientific details.”

He said the search warrant affidavits offered only incomplete data on how the letter anthrax was linked genetically to Dr. Ivins’s lab to the letters and almost nothing on the preparation of the powder.

The other, Jonathan B. Tucker, a biological warfare expert on the staff of a federal commission for the prevention of terrorism with unconventional weapons, said the documents contained “a number of gaps and inferences.”

The F.B.I. made no mention of handwriting analysis, for example, that might tie Dr. Ivins to the attack letters, Dr. Tucker said.

“It’s not an open-and-shut case,” he said. “There are some pieces of evidence that are much more compelling than others, and a number of loose ends that haven’t been tied.”

William J. Broad, Eric Lipton and Sarah Abruzzese contributed reporting from Washington, and Nicholas Wade from New York.

The F.B.I. seems convinced that it has finally solved the long-festering case of who mailed the anthrax letters that killed five people in 2001. Yet its description of the evidence pointing to a mentally disturbed Army bioweapons expert as the sole culprit leaves us uncertain about whether investigators have pulled off a brilliant coup after a bumbling start — or are prematurely declaring victory, despite a lack of hard, incontrovertible proof.

Federal agents relied on sophisticated scientific tests and laborious investigative work to conclude that only Dr. Bruce Ivins, who killed himself last week, could have made and mailed the anthrax used in the letters. They say that recently developed tests enabled them to identify telltale genetic mutations in the anthrax and to show that it came from a flask kept by Dr. Ivins at the Army laboratories at Fort Detrick in Frederick, Md.

More than 100 people might have had access to the deadly substance, but over a four-year period, investigators gradually eliminated suspects until only Dr. Ivins was left.

None of the investigators’ major assertions, however, have been tested in cross-examination or evaluated by outside specialists. It is imperative that federal officials make public all of their data so independent experts can judge whether the mailed anthrax was indeed identical to Dr. Ivins’s supply and only that supply.

It is also critical for officials to explain more fully how they eliminated the many other people with access to the material.

The investigators came up with lots of circumstantial evidence to bolster their case. The envelopes used in the mailings had print defects that indicate that they could only have been bought at a small number of post offices, including one where Dr. Ivins had a mailbox under an assumed name. Dr. Ivins had obtained equipment that could turn his wet anthrax into the dry spores that were mailed.

In the days before the mailings, he worked long hours alone at night and on weekends, outside his usual pattern. E-mail messages indicate that he was mentally disturbed and worried about an anthrax vaccine project that was failing, a possible motive for mailings to generate public fear about anthrax. There is also evidence that he had a history of driving to other locations to mail packages anonymously.

But there is no direct evidence of his guilt. No witness who saw him pouring powdered anthrax into envelopes. No anthrax spores in his house or cars. No confession to a colleague or in a suicide note. No physical evidence tying him to the site in Princeton, N.J., from which the letters are believed to have been mailed.

Because Dr. Ivins killed himself before he could be indicted, there will be no opportunity for an adversarial testing of the F.B.I.’s conclusions. The bureau, unfortunately, has a history of building circumstantial cases that seem compelling at first but ultimately fall apart. Congress will need to probe the adequacy of this investigation — and to insist that federal officials release as much evidence as possible, so the public can be assured they really did get the right person this time.

WASHINGTON — In December 2002, federal investigators scoured an icy pond on a snow-covered mountain near Frederick, Md., hunting for clues that would lead to the anthrax killer.

As they worked, the Army microbiologist now believed to be responsible for the five deaths stood calmly in their midst, chatting, smiling and watching.

Bruce E. Ivins, the scientist, mingled with the investigators in a military tent as a Red Cross volunteer, serving coffee, doughnuts and chocolate bars to agents of the Federal Bureau of Investigation and members of the search team.

Law enforcement officials hustled him away after they realized he was an anthrax researcher who could compromise the investigation, according to Red Cross volunteers who were there.

Dr. Ivins seemed embarrassed by it all, prompting his friends to tease him about the incident.

Nearly five years passed before the F.B.I. turned its attention to the man who had stood on the sidelines of the hunt that day. And Miriam Fleming, who was there as the divers plunged into the murky waters searching for evidence, said she still could not quite believe that the man identified as the anthrax killer was cheerfully working by her side.

“He was kind of goofy, but he was always in a good mood,” said Ms. Fleming, who was a Red Cross volunteer then. “He seemed so normal.”

She added: “Now we have to figure it out: Who was the real Bruce Ivins?”

Last week, Dr. Ivins killed himself as the authorities were preparing to indict him in the mailing of the anthrax letters in 2001. Yet as his friends and colleagues note, Dr. Ivins was almost always in plain sight, offering assistance — and misleading information, officials say — to federal agents running the nation’s longest and most expensive bioterrorism inquiry.

In the early days after the letter attacks in September and October 2001, Dr. Ivins joined about 90 colleagues at the Army Medical Research Institute of Infectious Diseases in a round-the-clock push to test thousands of samples of suspect powder to see if they were anthrax. He even helped to analyze a letter sent to Senator Tom Daschle, Democrat of South Dakota, and went to the Pentagon to discuss the results.

Jeffrey Adamovicz, who was Dr. Ivins’s supervisor at the time, remembers the day the scientists opened that envelope, placed in a double-sealed bag inside a protective hood designed to deal with dangerous pathogens.

“The anthrax was floating around inside the bag,” Mr. Adamovicz said. “It was very scary.”

He said he turned to Dr. Ivins and said, “That stuff is amazing.”

“Yes, it is unbelievable,” he recalled Dr. Ivins replying. “I have never seen anything like that.”

Months later, as the F.B.I. focused on the Army laboratory at Fort Detrick, Md., as a possible source of the anthrax, Dr. Ivins twice submitted samples from his own supplies that did not match the deadly spores used in the attack. Investigators later concluded he had chosen irrelevant samples to throw them off his trail.

He also repeatedly offered the F.B.I. the names of colleagues at Fort Detrick who he said might be potential suspects in the letter attacks, according to court documents.

And in recent years, as his status shifted gradually from adviser to suspect, Dr. Ivins continued to cooperate with the F.B.I., answering questions from agents and from a grand jury, said his lawyer, Thomas M. DeGonia.

Mr. DeGonia, who maintains that his client was innocent, denied the F.B.I.’s assertions that Dr. Ivins had tried to thwart the investigation.

“I think he continued to be motivated to genuinely help,” Mr. DeGonia said. “He was willing to cooperate to the very end.”

But officials are skeptical. In a news conference this week, a United States attorney, Jeffrey Taylor, said it was clear that Dr. Ivins “made far-reaching efforts to blame others and divert attention from himself.”

Mr. Taylor suggested that Dr. Ivins might have mailed the letters out of concern for the future of an anthrax vaccination program for the military, which was threatened after soldiers had claimed they were sickened by the injections. He said Dr. Ivins, who had dedicated his career to the anthrax vaccine, might have plotted the attacks to create “a scenario where people all of a sudden realize the need to have this vaccine.”

F.B.I. officials say Dr. Ivins, a skilled microbiologist with access to the crucial supply of anthrax, was on a short list of likely suspects at the Army laboratory. He wrote dozens of papers on anthrax defenses and held at least two patents on ways to fight the germ. He also distributed the pathogen to scientific colleagues.

Friends say his intense interest in science was apparent when he was growing up in Lebanon, Ohio, where his father owned a drugstore.

In high school, he joined the pep club and the current events club, ran cross-country and starred in the senior class play. But his heart was in science. He won state science fair prizes and was inducted into the National Honor Society.

While other students made science projects using kitchen supplies, Dr. Ivins used a high-powered microscope that his parents bought for him and wrote a detailed paper about the micro-organisms he had examined.

“I don’t know if the word ‘nerd’ was used in those years, but it would apply,” said Dean Deerhake, Dr. Ivins’s high school chemistry teacher.

Former classmates described him as the smartest student in class, but he never really fit in. He had few close friends. He never had a date, they said, not even when he went to the prom.

And his family, while prominent and privileged, was quite troubled. In an e-mail message written in recent years, Dr. Ivins described his mother as “an undiagnosed paranoid schizophrenic” and his years before college as a period of “isolation and desolation.”

But after Dr. Ivins received his doctorate in microbiology at the University of Cincinnati and joined the Army’s biodefense institute at Fort Detrick in the 1970s, his career took off.

At first Dr. Ivins worked on cholera, but, starting in the early 1980s, he turned his attention to anthrax. He quickly became an international expert on the Ames strain, a particularly virulent form that federal officials have identified as the type used in the 2001 attacks. And he worked to develop vaccines against the disease.

“I would not describe him as brilliant or some kind of genius,” said W. Russell Byrne, who supervised Dr. Ivins for several years. “But he was very diligent. Very careful. Very meticulous.”

In Frederick, where he lived, Dr. Ivins was known as a happy-go-lucky guy who composed funny songs, helped neighbors with their yard work and entertained friends with his juggling and piano playing.

“It is just very difficult to reconcile the person we had known with the person the F.B.I. says he was,” said Robert Duggan, who for many years lived down the street from Dr. Ivins, his wife and their two adopted children.

But in 2000, Dr. Ivins’s careful record-keeping landed him in trouble. Opponents of the Pentagon’s policy mandating vaccination of active-duty troops had filed Freedom of Information Act requests for notebooks of the scientists at Fort Detrick involved in research on the anthrax vaccine.

Dr. Ivins had written in one notebook that the vaccine had made some animals sick, Dr. Byrne recalled. When the notebook became public, critics of the vaccine cited it as evidence that the vaccine not only might have been ineffective but was also perhaps making military personnel ill, said Mark S. Zaid, a lawyer who filed the lawsuit.

It was a frustrating turn of events for the scientists who had worked so hard to produce safe vaccines, both the one that was being challenged and a separate, more advanced vaccine that they were developing.

In retrospect, Mr. Zaid said he wondered if the incident might have deeply angered Dr. Ivins, threatening his years’ worth of research on anthrax vaccines, as the opponents of the Pentagon program ultimately succeeded briefly in getting the military to discontinue mandatory vaccinations.

That remains uncertain. What is clear is that when the anthrax attacks occurred, Dr. Ivins was eager to participate in the inquiry and to talk about it.

He was particularly struck by the airborne nature of the deadly strain of anthrax found in the letters. Ellen Byrne, the wife of Dr. Byrne, remembers Dr. Ivins explaining how crafty the perpetrator had been to get the anthrax to be so finely ground that it was almost as light as air.

At a party, Dr. Ivins leaned over and, with his long, bony fingers, illustrated how the powder just sort of floated.

“He was just astonished,” Mrs. Byrne said. “Flabbergasted.”

“This was something that none of us ever dreamed of,” she remembered him saying. “It just could not be weighed. It could not be measured. It just hovered.”

At the time, though, Dr. Ivins was quietly growing increasingly troubled. He was taking antidepressant and antipsychotic medications to try to control what he described as “incredible, paranoid delusional thoughts,” fearful that his vaccine program would not survive. In November 2001, he sent photos by e-mail of himself working in the laboratory on the Ames strain of Bacillus anthracis to a group of people, including Nancy L. Haigwood, a microbiologist who had met him when he was doing postdoctoral work in North Carolina.

“I think this was someone who desperately wanted attention drawn to himself as a special person, as a hero,” Dr. Haigwood said.

In 2002, after the American Society for Microbiology sent an e-mail query on behalf of the F.B.I. to members asking if they knew anyone who could have carried out the attacks, Dr. Haigwood remembered Dr. Ivins’s e-mail message and went to the government with her suspicions.

That year, when the Red Cross called its members to support a weeklong law enforcement mission in the mountains near Frederick, Dr. Ivins offered to help. The mission was supposed to be a secret, but many people knew that the investigators were working on the anthrax killings.

The investigators had focused on another researcher who had worked at Fort Detrick, Steven J. Hatfill. Dr. Hatfill had worked on viruses, not anthrax, during his time at the Army laboratory, from 1997 to 1999, but agents were searching the pond in the woods near Frederick for any anthrax-making equipment that he might have disposed of there.

Humvees rumbled up the twisting dirt roads, and divers plunged into the water as Dr. Ivins took his post in the tent. He helped fix a leak in the corner and then helped distribute the supplies, until the investigators led him away.

For years afterward, he and his friends would joke whenever they went off to do relief work about whether the authorities were coming to get Dr. Ivins.

“He’d say, ‘Is it O.K. if I go?’ ” said Barb Christie, a Red Cross volunteer, recalling the conversations. “ ‘Nobody’s going to take me out, are they?’ And we’d all laugh.”

Scott Shane, William J. Broad, Sarah Abruzzese and Ginger Thompson contributed reporting.

WASHINGTON — Six years after labeling Steven J. Hatfill a “person of interest” in the anthrax attacks, the Justice Department formally exonerated him on Friday and told his lawyer it had concluded that Dr. Hatfill “was not involved in the anthrax mailings.”

The department agreed in June to pay $4.6 million to settle Dr. Hatfill’s lawsuit against the government, but until Friday it had conspicuously avoided declaring that he had nothing to do with the attacks.

Jeffrey A. Taylor, the United States attorney for the District of Columbia, said in the letter to Dr. Hatfill’s lawyer that “we have concluded, based on laboratory access records, witness accounts and other information, that Dr. Hatfill did not have access to the particular anthrax used in the attacks, and that he was not involved in the anthrax mailings.”

The lawyer, Thomas G. Connolly, declined to comment Friday, except to say that “the letter speaks for itself.”

The formal exoneration underscored the wrong path that the investigation had taken before the F.B.I. began looking two years ago at a colleague of Dr. Hatfill, another military scientist named Bruce E. Ivins.

The Justice Department said this week that it was now convinced that Dr. Ivins — who died 11 days ago after taking an overdose of painkillers — was the anthrax killer and that he had acted alone in a crime that killed five people and shook the country.

Leading lawmakers have promised to examine the course of the F.B.I.’s investigation and called on the Justice Department to explain how a scientist who appeared to have been hiding in plain sight was missed for so long. Dr. Ivins, who had specialized in anthrax vaccines at a military research facility at Fort Detrick, Md., assisted the F.B.I. in the early stages of its investigation, but his mental instability and suspicious habits appeared to have been well known to many acquaintances and co-workers.

Senator Charles E. Grassley, the Iowa Republican who sits on the Judiciary Committee and has been a critic of the pace of the F.B.I.’s anthrax investigation, said in a telephone interview Friday that Congress needed to conduct hearings to determine what went wrong in the investigation.

“We’ve had a seven-year investigation and $15 million spent on it and one of the ‘people of interest’ bought off for $5.8 million over what was obviously an F.B.I. screw-up,” Mr. Grassley said. “We need answers.”

The F.B.I. bought Dr. Hatfill an annuity that will be worth $5.8 million to him and his lawyers.

The House Energy and Commerce Committee will expand its investigation into the risks of government laboratories to include the screening of personnel at Fort Detrick and elsewhere, said the committee chairman, Representative John D. Dingell, and the chairman of the investigations subcommittee, Representative Bart Stupak, both Democrats of Michigan. They urged a moratorium on construction of laboratories housing research into highly infectious agents.

Beginning in 2002, within months of the anthrax attacks in the fall of 2001, Dr. Hatfill became the sole suspect publicly linked to the case, in part through news reports and in part through the public statements of the authorities. John Ashcroft, who was then the attorney general, said in an unusual pronouncement in August 2002 that Dr. Hatfill was “a person of interest” in the anthrax investigation.

Dr. Hatfill declared his innocence from the start, saying the notoriety threatened to ruin his career and his life. “I am not the anthrax killer,” he declared outside his lawyer’s office in an emotional pronouncement a week after Mr. Ashcroft’s statement.

But the F.B.I. searched his home and maintained nearly round-the-clock surveillance on him for years.

In June, the Justice Department agreed to the multimillion-dollar settlement with Dr. Hatfill to end the lawsuit he had brought alleging that his privacy was violated by the government’s leaks linking him to the case. Dr. Hatfill also sued The New York Times and the columnist Nicholas D. Kristof, saying that columns Mr. Kristof wrote about the case had libeled him by suggesting that he might be the anthrax mailer. That lawsuit was dismissed last year, but Dr. Hatfill has appealed the dismissal.

The Justice Department’s announcement of its settlement with Dr. Hatfill, unlike some of its past agreements with people wrongfully suspected in investigations, did not include any exoneration of Dr. Hatfill or an apology to him. Officials said later that when they reached the settlement, they did not want to alert Dr. Ivins to their possible interest in him by declaring that they had cleared Dr. Hatfill.

At a news conference on Wednesday laying out the case against Dr. Ivins, officials went out of their way to avoid mentioning Dr. Hatfill by name, and they stopped short of clearing him.

“With respect to the other individual you mentioned,” Joseph Persichini Jr., the head of the F.B.I.’s Washington field office, told a reporter who asked about Dr. Hatfill, “we were able to determine that at no time could that individual be put in the presence of that flask from which these spores came.”

But Dr. Hatfill’s lawyers were said to be unsatisfied and pressed the department for an explicit exoneration, according to one person close to the case who spoke on condition of anonymity. 

WASHINGTON — Military personnel, under the threat of court-martial, were refusing inoculations of an anthrax vaccine. The vaccine’s sole manufacturing plant was ordered to shut down. Researchers were turning up evidence possibly linking the vaccine to illnesses of soldiers during the Persian Gulf war of 1991.

It was hardly the thank you that Dr. Bruce E. Ivins expected for his years of labor to produce a vaccine that would protect military personnel from an anthrax attack by the Iraqi leader Saddam Hussein or some other adversary.

The criticism, which reached its peak in 2000 and early 2001, was clearly starting to get on Dr. Ivins’s nerves. “I think the **** is about to hit the fan ... big time,” he wrote in a July 2000 e-mail message about the inoculation program, according to a government affidavit. “It’s just a fine mess.”

This turmoil has now been cited by federal investigators as a key part of the reason they believe that Dr. Ivins sent out anthrax-laced letters in the fall of 2001 — as such an attack would, in a single stroke, have eliminated the skepticism and second guessing about the need for an anthrax vaccine.

The investigators suggest that Dr. Ivins had been struggling with psychological problems, and was on medication and undergoing counseling after being overcome by what he described as paranoid, delusional thoughts. The trouble with the vaccine, they argue, may have been enough to set him off.

But Dr. Ivins’s former colleagues reject that two-part theory, saying it is just one of many flaws in the evidence presented by the government in an unconvincing case.

There was a real threat, the former colleagues acknowledged, that the anthrax vaccine Dr. Ivins had worked on during that period, known as Anthrax Vaccine Absorbed or AVA, might be pulled from the market

Most troubling were problems at the Michigan manufacturing plant, which had been shut down in 1998 after the Food and Drug Administration uncovered serious flaws.

Dr. Ivins and other researchers, however, had been working on a more advanced alternative vaccine — considered safer and more effective — so there was no reason for such a rash act, his former colleagues say.

“There was a lot of consternation, a lot of pressure to rescue this thing,” said Jeffrey Adamovicz, one of Dr. Ivins’s fellow researchers at the time. “But if AVA failed, he had his next vaccine candidate. It was well on its way to what looked to be a very bright future.”

The vaccine controversy erupted in the late 1990s, after the Defense Department ordered the inoculation of all 2.4 million active duty and reserve troops, starting with those most likely to confront biological attacks in war zones, partly because Iraq had confirmed that it once had a large stockpile of anthrax that was destroyed after the first Persian Gulf war.

By 2000, more than 570,000 military personnel had complied with the order, and hundreds had filed an “adverse event report” after receiving the shots, citing reactions that included fatigue, dizziness and muscle pain, and more serious conditions like thyroid disorders and rhabdomyolysis, a muscle ailment.

Congressional hearings were held, and dozens of House members signed a letter to the Pentagon calling the mandatory vaccination program “a flawed policy that should be immediately stopped.”

Protests were also organized.

“What the government is doing is wrong, and it is time to wake up America from its comfortable stupor and say ‘no more,’ ” said a Pennsylvania woman, Gloria Graham, at a 2000 protest over the vaccine, which Ms. Graham said had sickened her son.

The Army Medical Research Institute of Infectious Diseases, at Fort Detrick, Md., where Dr. Ivins worked, had been assigned by the Defense Department to help BioPort, the company that owned the Michigan manufacturing plant, to fix any problems so production could resume.

“Unfortunately, since the BioPort people aren’t scientists, the task of solving their problem has fallen on us,” Dr. Ivins wrote in a June 2000 e-mail message.

The situation became dire as the vaccine supply dwindled, leading Dr. Ivins to speculate openly that the program might be halted. “That would be bad for everyone concerned, including us,” he wrote. “I’m sure that blame will be spread around.”

The pressure was intense for the team at Fort Detrick that had been working on the effort, a group of about half a dozen scientists and technicians, said Dr. Adamovicz, Dr. Ivins’s former colleague.

“It was a big concern for us,” Dr. Adamovicz said in an interview this week. “We wanted obviously to see this vaccine succeed.”

The stakes were particularly high for Dr. Ivins, who, for nearly a decade, had been leading experiments in which laboratory animals — rabbits, monkeys and mice — were injected with vaccines that each had slightly different additives in an effort to increase their effectiveness.

Critics of the program were accusing the Defense Department of using one of the experimental formulas, which featured an oil-based additive called squalene, in vaccines given to military personnel in the gulf war, a decision, they contended, that may have caused autoimmune diseases among returning soldiers.

“It is well documented that the U.S. military has a history of administering experimental vaccines to the troops,” said Gary Matsumoto, who was doing research on a book on the anthrax program and who had submitted Freedom of Information requests to the Army requesting access to Dr. Ivins’s laboratory notebooks.

The Defense Department denied conducting such experiments on troops and defended the vaccine, saying it was both safe and effective, and necessary to protect the military from a possible attack. Dr. Ivins’s notebooks, which were released to the public, suggested, however, that he had found that the vaccine might be making some of the test animals sick.

“Although all vaccinated monkeys survived, they appeared to be sick over the course of two weeks,” Dr. Ivins’s laboratory report said.

In his e-mail messages, Dr. Ivins expressed particular contempt for Mr. Matsumoto and his requests for copies of internal Army test results.

“We’ve got better things to do than shine his shoes and pee on command,” Dr. Ivins wrote, in August 2001, about Mr. Matsumoto. “He’s gotten everything from me he will get.”

What the Justice Department has not produced is evidence documenting that Dr. Ivins’s frustrations motivated him to retaliate with the anthrax letters.

Gerard P. Andrews, another of Dr. Ivins’s former colleagues, said he knew that Dr. Ivins was frustrated, but that he doubted that Dr. Ivins would consider such a step.

“Nothing is unimaginable,” Dr. Andrews said. “But I would definitely say it is doubtful.”

ON Wednesday, the United States Justice Department revealed its evidence that Dr. Bruce E. Ivins, on his own, committed the worst act of bioterrorism in the country’s history. This 18-year veteran scientist of the United States Army Medical Research Institute of Infectious Diseases at Fort Detrick in Frederick, Md., is accused of killing five people and sickening 17 others in the fall of 2001. Dr. Ivins died on July 29 of an apparent suicide without a chance to give his side of the story.

After reading the affidavits and listening to the Justice Department briefing, I was both disheartened and perplexed by the lack of physical evidence supporting a conviction.

Dr. Ivins was a friend and colleague of mine for nearly 16 years. We worked together at Fort Detrick. He was a senior scientist, and I was, first, a bench scientist and, from 1999 to 2003, the chief of the bacteriology division.

The Justice Department has presented different types of evidence to support its argument that Dr. Ivins was the person who mailed anthrax to Tom Brokaw, Tom Daschle and others in September and October of 2001. Much of this evidence is outside the realm of science: Dr. Ivins’s alleged fixation with a sorority; strange comments in excerpts from his e-mail messages; a connection to a Greendale school that might or might not explain the fictitious return address on anthrax mailings. I will not address these points beyond noting that they are highly circumstantial.

As a scientist, however, I feel compelled to comment on what should have been the Federal Bureau of Investigation’s strongest link between Dr. Ivins and the terrible crime — deadly anthrax spores. In the summary of its findings, the F.B.I. states that investigators used four different genetic techniques to match the anthrax-laced attack letters to a unique DNA footprint of a single anthrax spore preparation in one flask that had been in Dr. Ivins’s custody.

Sounds reasonable. Yet the investigators present no details on the scientific methods they used to make this match or how they employed them. That’s a problem, because without such detail it is hard to tell if they specifically ruled out a similar match between the anthrax in the letters and anthrax preparations with the same DNA footprint kept at a number of other labs around the country. The basic methods of genetic analysis are well known. Why not provide enough detail about their procedure to enable other scientists to tell whether they could actually single out Dr. Ivins’s spore preparation as the culprit?

The investigators fail to address another underlying problem with their anthrax match: that Dr. Ivins was an investigator in the case before he was a suspect. After the anthrax attack, Dr. Ivins himself worked directly with the evidence. The F.B.I. asked Dr. Ivins to help them with the forensics in the case by analyzing the contents of suspicious letters. And he did so for years, until the authorities began to suspect that the anthrax spores used in the mailings might have originated from his lab.

Dr. Ivins, for instance, was asked to analyze the anthrax envelope that was sent to Mr. Daschle’s office on Oct. 9, 2001. When his team analyzed the powder, they found it to be a startlingly refined weapons-grade anthrax spore preparation, the likes of which had never been seen before by personnel at Fort Detrick.

It is extremely improbable that this type of preparation could ever have been produced at Fort Detrick, certainly not of the grade and quality found in that envelope.

But even leaving that aside, there are important questions left unanswered. First, isn’t it possible that the manipulation of the contents of the anthrax letters in Dr. Ivins’s laboratory might have contaminated the work environment enough to potentially jeopardize the integrity of subsequent samples taken from the lab? Might that perhaps explain why the anthrax powder used in the attacks was later found to have the same DNA footprint as the other anthrax preparations in Dr. Ivins’s lab? At the very least, wouldn’t this call his guilt into doubt?

It was as if a gun used in a murder was unintentionally returned to the scene of the crime several days after the murder. What are the legal implications of such a possibility? Wouldn’t a court be especially cautious in considering evidence involving a weapon in such circumstances?

This case is apparently closed with Dr. Ivins’s death. But until the F.B.I. discloses its scientific testing methods and data, many questions will remain unanswered.

Gerry Andrews is an assistant professor of microbiology at the University of Wyoming.

When Perry Mikesell, a microbiologist in Ohio, came under suspicion as the anthrax attacker, he began drinking heavily, family members say, and soon died. After a doctor in New York drew the interest of the F.B.I., his marriage fell apart and his practice suffered, his lawyer says. And after two Pakistani brothers in Pennsylvania were briefly under scrutiny, they eventually had to leave the country to find work.

The Federal Bureau of Investigation’s path to Bruce E. Ivins, the Army scientist who committed suicide late last month as federal officials moved closer to indicting him for the 2001 anthrax letter attacks, was long and tortuous. Before the investigators settled on Dr. Ivins — and his defenders still say the F.B.I. hounded an innocent man to death — they had focused on Steven J. Hatfill, another Army researcher, for several years.

But along the way, scores of others — terrorists, foreigners, academic researchers, biowarfare specialists and an elite group of Army scientists working behind high fences and barbed wire — drew the interest of the investigators. For some of them the cost was high: lost jobs, canceled visas, broken marriages, frayed friendships.

At the Army biodefense laboratory in Frederick, Md., where Dr. Ivins worked, the inquiry became a murder mystery, the cast composed of top scientists eyeing one another warily over vials of lethal pathogens.

“It was not pleasant,” recalled Jeffrey J. Adamovicz, a former official there. “There was a general sense of paranoia that they were going to get somebody no matter what.”

Some critics fault the F.B.I.’s investigation as ignorant, incompetent and worse. Representative Rush D. Holt, a New Jersey Democrat who was a Princeton University physicist, said that the disclosures linking Dr. Ivins to the crime notwithstanding, the inquiry was “poorly handled” and “resulted in a trail of embarrassment and personal tragedy.”

The bureau’s defenders, though, say it did what was necessary to track down a dangerous killer.

“You do the best you can, and it’s not always pretty,” said Robert M. Blitzer, a former director of the F.B.I.’s section on domestic terrorism. “Here you have a bunch of people dead and several diminished, and you’re charged with solving the crime. You try not to step on people’s toes, but sometimes it happens.”

Over seven years, the anthrax investigators conducted nearly 100 searches and more than 9,000 interviews in the most complex criminal case in bureau history. They hunted an attacker who, in September and October 2001, had mailed anthrax-laden envelopes that killed 5 people, sickened 17 others and threw the nation into a panic.

Early on, with more zeal than solid information, agents turned on three Pakistani-born city officials in Chester, Pa. One, Dr. Irshad Shaikh, was the health commissioner; his brother, Dr. Masood Shaikh, ran the lead-abatement program. The third, Asif Kazi, was then an accountant in the finance department.

Mr. Kazi was sitting in his City Hall office one day in November 2001 when F.B.I. agents burst in and began a barrage of questions.

“It was really scary,” Mr. Kazi recalled in an interview last week. “It was: ‘What do you think of 9/11? What do know about anthrax?’ ”

Across town, an agent pointed a gun through an open window at Mr. Kazi’s home while others knocked down the front door as his wife was cooking in the kitchen. At the Shaikh brothers’ house, agents in bioprotection suits began hunting for germ-making equipment and carted away computers.

None of the three men had ever worked with anthrax. But for days, they were on national television as footage of the searches ran on a video loop and news announcers wondered aloud if they were the killers.

The men were cleared after it turned out that a disgruntled employee had sought revenge by calling in a bogus tip. But for all three, trouble followed. The Shaikhs’ path to citizenship was disrupted, their visas ran out and both had to find work abroad, Mr. Kazi said.

Mr. Kazi, already a citizen, was searched and interrogated for as long as two hours every time he traveled back from visiting his brother in Canada. Only about a year ago was his name removed from a watch list, allowing him to travel freely.

When Mr. Kazi heard that Dr. Ivins was said to be the culprit in the attacks, he had only one request.

“We’d just like our names cleared,” Mr. Kazi said. “There’s no problem for people who know us. But out in the community, someone might still think, ‘Maybe these guys were guilty.’ ”

In late 2001, agents discovered that the germ used in the attacks was not foreign in origin but a domestic strain. That prompted the F.B.I. to focus mainly on scientists inside the United States. Casting a wide net, the bureau sent a letter to the 30,000 members of the American Society for Microbiology. “It is very likely,” it said, “that one or more of you know” the attacker.

The bureau began looking at biodefense insiders like Mr. Mikesell, an anthrax specialist who had worked in the 1980s and 1990s with Dr. Ivins at the Army Medical Research Institute of Infectious Diseases at Fort Detrick, in Frederick. He had then joined Battelle, a military contractor in Columbus, Ohio, that became deeply involved in secret federal research on biological weapons.

In 2002, Mr. Mikesell came under F.B.I. scrutiny, officials familiar with the case said. He began drinking heavily — a fifth of hard liquor a day toward the end, a family member said.

“It was a shock that all of a sudden he’s a raging alcoholic,” recalled the relative, who spoke on the condition of anonymity because of family sensitivities.

By late October 2002, Mr. Mikesell, 54, was dead, his short obituary in The Columbus Dispatch making no mention of his work with anthrax or the investigation. “He drank himself to death,” the relative said.

Dr. Hatfill, who worked at Fort Detrick from 1997 to 1999, also drew the investigators’ attention. He loved covert exploits and padded his résumé, habits that intrigued F.B.I. agents and, not long after that, reporters.

In June 2002, officials tipped off television stations that the bureau would search Dr. Hatfill’s apartment, just outside the gates to Fort Detrick. Later, F.B.I. agents told the woman he was living with at the time that he was a murderer and warned that she could be charged as an accomplice if she failed to tell all. At a teary press conference in August 2002, Dr. Hatfill protested his innocence.

For at least a year, F.B.I. surveillance teams followed him — and in one remarkable encounter, a car that was trailing him ran over his foot. (Dr. Hatfill, not the agent, was given a ticket.)

But there was no arrest, and Dr. Hatfill, who said his career was ruined, fought back, filing a series of lawsuits, including against The New York Times. In June, long after the hunt had been narrowed to Dr. Ivins, the government agreed to pay Dr. Hatfill $4.6 million. On Friday, the Justice Department issued a statement exonerating him.

Another casualty was Kenneth M. Berry, an emergency room physician with a strong interest in bioterrorism threats. In August 2004, agents raided his colonial-style home and his former apartment in Wellsville, a village in western New York, as well as his parents’ beach house on the Jersey Shore.

In scenes replayed for days on local television stations, the authorities cordoned off streets as agents in protective suits emerged from the dwellings with computers and bags of papers, mail and books.

“He was devastated,” Dr. Berry’s lawyer at the time, Clifford E. Lazzaro, said in an interview. “They destroyed his marriage and destroyed him professionally for a time.”

By 2005, thanks to new genetic testing, the F.B.I. had traced the anthrax in the letters to a single flask at Fort Detrick. Dr. Ivins had created and controlled the batch of deadly germs. But more than 100 scientists potentially had access to the pathogens.

For decades, the researchers of Fort Detrick had worked to build defenses against deadly germs used in war, mainly by creating new vaccines. They considered themselves patriots. In the early days of the anthrax investigation, the experts — including Dr. Ivins — threw themselves into helping the F.B.I., working around the clock.

Increasingly, though, the scientists found themselves viewed as potential culprits in the nation’s worst case of bioterrorism.

Dr. Adamovicz, the former Fort Detrick official, said the bacteriological division, which eventually had about 100 people including technicians and assistants, was like a family. But the growing air of mutual suspicion caused conversations to become stilted, even as some scientists became increasingly agitated and isolated from friends and colleagues.

“It became a game to talk in platitudes without mentioning the specifics,” Dr. Adamovicz said. “You had to.”

A least a dozen members of the division eventually were called to testify before a grand jury. “We were unclear on whether we were all suspects or whether there were specific suspects,” Dr. Adamovicz recalled.

The air of growing distrust ended some relationships. At one point, Dr. Ivins was advised by his lawyer to stop speaking with Henry S. Heine, an anthrax colleague. Dr. Ivins was led to believe that Dr. Heine might have raised questions about him.

“They implied that Hank was pointing the finger at him,” recalled W. Russell Byrne, a retired Army doctor who once supervised Dr. Ivins. “They told Bruce that ‘Hank Heine is not your friend.’ Then Bruce’s lawyer told him not to talk to Hank anymore.”

And even Dr. Ivins, according to court documents, began pointing his finger at specific colleagues as suspects.

Dr. Heine, who said he considered himself a close friend of Dr. Ivins, confirmed that Dr. Ivins had been warned to stop speaking with him, but Dr. Heine said he believed it was part of the F.B.I. strategy to isolate friends from one another. He added that although he did appear before the grand jury, he never pointed the finger at Dr. Ivins, and he still believes that Dr. Ivins was not involved in the anthrax letter mailings.

“I was Bruce’s big brother,” Dr. Heine said. “I needed to look out for him. And they needed to separate us.”

Dr. Byrne, who did not know of Dr. Ivins’s history of deep psychological problems that was disclosed by federal officials last week, said he could see signs of the growing stress Dr. Ivins was under as the investigation seemed to focus on him. One day, in March 2008, he showed up for a Sunday church service with a black eye.

“The F.B.I. been roughing you up?” Dr. Byrne recalled joking.

Last month, Dr. Ivins told an Army colleague that his experience of F.B.I. pressure was similar to what Mr. Mikesell went through.

“Perry drank himself to death,” the colleague recalled Dr. Ivins as saying some two weeks before he killed himself.

Federal officials say they are confident Dr. Ivins was responsible for the anthrax attacks, even if his suicide means their case will not be proved in court. And they reject criticism from lawmakers and others about the conduct of the investigation and express no regret about those who were caught up in it.

The F.B.I. director, Robert S. Mueller III, in his first public comments since the presentation of the evidence against Dr. Ivins on Wednesday, said Friday that he was proud of the inquiry.

“I do not apologize for any aspect of the investigation,” he told reporters. It is erroneous, he added, “to say there were mistakes.”

Eric Lipton contributed reporting.

College Park, Md.

THE government’s charge that Dr. Bruce Ivins, a top Army biodefense scientist, was responsible for the 2001 anthrax mailings has focused renewed attention on the important question of whether we are adequately prepared to protect against a future bioweapons attack. More than $20 billion has been spent on biodefense research since 2001. But the genetic analysis demonstrating that the anthrax powder used in the 2001 letters was a formulation first made at the Army biodefense research center at Fort Detrick, Md., suggests that our biodefense program risks creating the very threat it is meant to fight.

Spending on biodefense research began to edge up after the Japanese cult Aum Shinrikyo’s failed attempts to develop and use bioweapons in Tokyo in the 1990s. After the anthrax letters killed five and injured 17 others, some argued that it was not a question of if, but of when terrorists would again use bioweapons against Americans, and biodefense spending exploded. At the National Institutes of Health, research on bioweapons agents has increased from $53 million in 2001 to more than $1.6 billion in 2008. During the same time, the Department of Defense has more than doubled its investment in biodefense, to more than $1 billion.

An unprecedented expansion of research facilities is also under way. Once these laboratories are completed, we will have 10 times as much lab space as we had in 2001 for working on the most dangerous agents — Ebola and Marburg viruses, for example — and 13 new regional labs for working on moderate and high-risk agents like tularemia and plague. Thousands of scientists are now working with bioweapons agents, many for the first time. More than 14,000 scientists have been approved to work with so-called select agents like anthrax that usually pose little threat to public health unless they are used as bioweapons.

Experienced anthrax researchers now speak of a community that has grown so large, so rapidly — more than 7,200 researchers are now approved to work with this deadly agent — they no longer know everyone else in the field.

Since the boom began, bioweapons agents have been mishandled in a number of incidents. In 2004, live anthrax was accidentally shipped to a children’s hospital research lab in Oakland, Calif., and three lab researchers at Boston University developed tularemia after being exposed to the bacteria that causes it. In 2006, researchers at Texas A&M were exposed to brucellosis and Q fever. As an investigator for the Government Accountability Office reported to Congress last fall, the greater number of researchers handling bioweapons agents has increased the risk of such accidents.

Even more worrying are the security risks. The United States’ own biodefense program has now been tied directly to the deadliest biological attack ever in the country. That alone demonstrates that we need a rigorous, fact-driven assessment of bioweapons threats, both from other counties and from terrorists, domestic and foreign. The first step is to ensure that we have a full public examination of all the government’s evidence in the 2001 anthrax mailings, so that we can find out what went wrong and how to keep it from happening again.

Then we must re-examine our overall biodefense research strategy, set clear priorities and strengthen the safety, security and oversight of laboratories working with dangerous agents. Rather than add more laboratories and create more research projects, we need to focus on key efforts in fewer facilities. This should include pursuing diagnostic techniques, vaccines and treatments that can be applied to more than one biological agent. Most of this research does not require working with actual deadly agents until the very final stages.

Our excess biodefense research capacity could then be used for research on everyday public health threats like tuberculosis and antibiotic-resistant bacteria, many of which have not received sufficient attention since 9/11.

To defend against bioweapons, we need not more but better research efforts. The probability that biological weapons will be used against Americans is low, but the consequences of such an attack could be devastating. We cannot meet the threat safely or effectively with a strategy that puts bioweapons agents in more and more people’s hands.

Elisa D. Harris is a senior research scholar at the Center for International and Security Studies at the University of Maryland.

WASHINGTON — Growing doubts from scientists about the strength of the government’s case against the late Bruce E. Ivins, the military researcher named as the anthrax killer, are forcing the Justice Department to begin disclosing more fully the scientific evidence it used to implicate him.

In the face of the questions, Federal Bureau of Investigation officials have decided to make their first detailed public presentation next week on the forensic science used to trace the anthrax used in the 2001 attacks to a flask kept in a refrigerator in Dr. Ivins’s laboratory at Fort Detrick, in Maryland. Many scientists are awaiting those details because so far, they say, the F.B.I. has failed to make a conclusive case.

“That is going to be critically important, because right now there is really no data to make a scientific judgment one way or the other,” Brad Smith, a molecular biologist at the Center for Biosecurity at the University of Pittsburgh Medical Center. “The information that has been put out, there is really very little scientific information in there.”

F.B.I officials say they are confident that their scientific evidence against Dr. Ivins, who killed himself last month as the Justice Department was preparing an indictment against him, will withstand scrutiny, and they plan to present their findings for review by leading scientists. But the scrutiny may only raise fresh questions.

The bureau presented forensics information to Congressional and government officials this week in a closed-door briefing, but a number of listeners said the briefing left them less convinced that the F.B.I. had the right man, and they said some of the government’s public statements appeared incomplete or misleading.

For instance, the Justice Department said earlier this month in unsealing court records against Dr. Ivins that he had tried to mislead investigators in 2002 by giving them an anthrax sample that did not appear to have come from his laboratory.

But F.B.I. officials acknowledged at the closed-door briefing, according to people who were there, that the sample Dr. Ivins gave them in 2002 did in fact come from the same strain used in the attacks, but, because of limitations in the bureau’s testing methods and Dr. Ivins’s failure to provide the sample in the format requested, the F.B.I. did not realize that it was a correct match until three years later.

In addition, people who were briefed by the F.B.I. said a batch of misprinted envelopes used in the anthrax attacks — another piece of evidence used to link Dr. Ivins to the attacks — could have been much more widely available than bureau officials had initially led them to believe.

Representative Rush Holt, the New Jersey Democrat who has followed the anthrax case closely and requested this week’s briefing from the F.B.I., said in an interview that he was not ready to draw any firm conclusions about the investigation. But he said: ‘The case is built from a number of pieces of circumstantial evidence, and for a case this important, it’s troubling to have so many loose ends. The briefing pointed out even more loose ends than I thought there were before.”

Naba Barkakati, an engineer who is the chief technologist for the Government Accountability Office and who also attended this week’s briefing, said of the F.B.I.’s forensics case against Dr. Ivins: “It’s very hard to get the sense of whether this was scientifically good or bad. We didn’t really get the question settled, other than taking their word for it.”

The bureau’s lab work has come under sharp criticism in recent years for problems over DNA analysis, bullet tracing and other important forensic technology. In 2004, the laboratory mismatched a fingerprint taken from the Madrid terror bombings to a lawyer in Portland, Ore., Brandon Mayfield, who was then arrested. He won a $2.8 million settlement.

With the main suspect in the anthrax killings now dead, F.B.I. officials say they realize they will again face tough scrutiny over the strength of their scientific evidence against Dr. Ivins. Indeed, conspiracy theories are already flourishing on many Web sites, with skeptical observers asking whether the Maryland scientist was set up to take the fall for the attacks or, worse yet, was a murder victim. The fact that the bureau pursued another scientist, Steven J. Hatfill, for years before agreeing to pay $4.6 million to settle a lawsuit he had filed and then later exonerating him has only fueled the skepticism.

“Do you believe Bruce Ivins was responsible for the anthrax attacks?” The Frederick News-Post, the hometown newspaper in Fort Detrick, asked its readers this week. (Of those who responded, 34 percent said no, compared with 26 percent who said yes.)

In its case against Dr. Ivins, the F.B.I. developed a compelling profile of an erratic, mentally troubled man who could be threatening and obsessive, as in his odd fascination with a sorority from his college days. But investigators were never able to place him at the New Jersey mailboxes where the anthrax letters were dropped, and the case against him relied at its heart on the scientific evidence linking the anthrax in Dr. Ivins’s laboratory to the spores used in the attacks.

It took the F.B.I. several years to develop the type of DNA testing that allowed them to trace the origins of the “attack strain,” as it was called, and they concluded that the anthrax that Dr. Ivins controlled was the only one of more than 1,000 samples they tested that matched it in all four of that strain’s genetic mutations.

Dwight Adams, a former director of the F.B.I. laboratory who was deeply involved in managing the anthrax genetic research until he left the bureau in 2006, said he was confident that the groundbreaking forensic effort would be validated by the broad scientific community.

Recalling the early skepticism that a genetic fingerprint of an anthrax could ever be obtained, Mr. Adams said, “I think the bureau and the national assets, including the national labs and others, that were applied as a team can very easily defend what they did and the results.”

But had Dr. Ivins lived and faced trial for the anthrax killings, Thomas M. DeGonia II, one of his lawyers, said his legal team would have quickly tried to have the genetic testing of the anthrax strains thrown out of court as unreliable. The type of testing the F.B.I. developed, he said “has never been proven or tested by the courts.”

Even if a jury had heard evidence about the genetic testing, Mr. DeGonia said the lawyers would have tried to show that many other scientists had access to that same strain of anthrax. He said the fact that the Justice Department had Dr. Ivins under investigation for perhaps two years or longer — and that it was executing search warrants in the case even after his death — suggests that the department itself had doubts.

“It’s interesting that they’re still attempting to gather evidence,” he said, “if the case is as strong as they say it is.”

LATE on Aug. 8, the Justice Department finally exonerated Steven J. Hatfill, acknowledging six years after labeling him a “person of interest” that he was not the man who killed five people with anthrax attacks on Congress and news organizations in 2001.

If the intent was to call as little attention as possible to what amounted to a painful admission of error — Hatfill said his life and career were ruined by government leaks that wrongly painted him as the murderer — the timing could not have been better. It was a summer Friday afternoon, and the news was about to be swamped by the opening ceremonies at the Olympics. Weeks earlier, in a terse, two-paragraph statement, the Justice Department had announced that it was settling a lawsuit by Hatfill with a deal that would cost taxpayers $4.6 million.

L. Lin Wood, an Atlanta lawyer who represented others who were dragged through the news but never charged — Richard Jewell, Gary Condit and the parents of JonBenet Ramsey — calls this the “whisper of innocence that could never drown out the shout of ‘guilty.’ ” The government has not apologized to Hatfill.

Nicholas D. Kristof, a Times Op-Ed columnist, intends to be more stand-up. He pointed to Hatfill as someone needing closer investigation in a series of columns in 2002 castigating the F.B.I. for “an unbelievably lethargic” investigation of the anthrax attacks. Now that Hatfill, a former government biologist, has been formally cleared, Kristof told me he plans to write a column looking back on the case and apologizing to Hatfill for any “extra scrutiny and upheaval the columns brought to him, and wrestling with the journalistic issues involved.”

Hatfill sued Kristof and The Times, but the case was dismissed, and Hatfill has lost two appeals. His attorney would not comment for this column.

Regardless of the legal outcome, Hatfill’s case poses uncomfortable journalistic questions that do not have easy answers. In reporting on a major criminal investigation, how do you balance the interests of the public in knowing as much as possible with the rights of individuals who come under suspicion, especially when the information comes from sources — often anonymous — whose motives aren’t clear?

“The trade-offs issue is tough,” Kristof said in an e-message from Beijing, where he is on a reporting trip. “I find the collision of the public interest in information with the private interest in privacy to be enormously difficult to resolve, with no good solution.”

He said that when the media interest is partly salacious or sensational — as in the cases of John and Patsy Ramsey, who were wrongly suspected in the murder of their daughter, and Condit, the former California congressman wrongly suspected of killing Chandra Levy — journalists should be “especially wary of harming the individuals who get caught up in prosecutorial interest.” But the anthrax case involved an urgent issue of national security, and news organizations had to be more aggressive, he said.

I agree, but I think Kristof marshaled the evidence and raised so many questions about Hatfill that he contributed to a cloud of suspicion over the wrong man at a time when, in hindsight, the F.B.I. should have been pursuing other leads.

Kurt Luedtke, a former newspaper editor, wrote “Absence of Malice,” a 1981 movie about the human devastation caused when a reporter accepts a leak from an unscrupulous prosecutor trying to coerce information from an innocent man. I asked Luedtke, an old friend and colleague, about the Hatfill case. “I agree that there is not an easy answer,” he said. “Of course the public is interested in whether the government is on the track of someone who may be responsible for the anthrax attacks. That is the news.” As for who it is, he said, the news media should say, “We’ll get back to you” with a name. But the hard part is when. Not until a person is charged? Only when sources will go on the record? If it looks like a guilty person is going free? When a news organization can independently develop its own information?

In his initial columns, Kristof identified Hatfill only as “Mr. Z.” Luedtke said he thought that was the right thing to do. But once Attorney General John Ashcroft called him “a person of interest” and Hatfill came forward to proclaim his innocence, Luedtke said, the media had no choice but to report it. “I think we’re prisoners of a process,” he said.

Toni Locy, a former USA Today reporter who was found in contempt of court in Hatfill’s suit against the government for refusing to reveal her sources, disagrees with withholding names. She said she was “very, very skeptical” about the case against Hatfill, but “our job is to inform the public, and the public has an interest in him. ... Putting a veil of secrecy over the criminal justice system is a very dangerous thing to do.” It also seems impossible in today’s hypercompetitive media world, with 24-hour cable news and the Internet. If one news organization decides not to name a suspect based on a leak, someone else will.

Kristof said he had been concerned about the potential impact of what he was writing. He said he tried to humanize Hatfill by writing that Mr. Z’s friends “are heartsick at suspicions directed against a man they regard as a patriot.” After Hatfill was identified, Kristof wrote that there “must be a genuine assumption that he is an innocent man caught in a nightmare.”

I asked Kristof if he regretted focusing so much on Hatfill when the point was to spur the F.B.I. to a more vigorous investigation. He said, “I think I should have tried harder to find a range of other examples to underscore the incompetence of the F.B.I. anthrax investigation.”

In the cases of the Ramseys, Condit and Jewell, the security guard who was wrongly suspected in the 1996 bombing at the Atlanta Olympics, it appears that much of the damage was done when reporters took leaks from anonymous official sources and ran them uncritically, creating what Wood, the lawyer, called “an unholy alliance between the media and law enforcement” to prosecute in the press. Kristof’s columns came from the opposite direction. He was criticizing law enforcement officials for being lax, and he said getting information from them was like pulling teeth.

Wood said he believes the news media should report the name of a suspect only if authorities will go on the record or if an arrest is imminent. Journalists should think hard before doing otherwise. They should test the information from leaks, treat it skeptically and, if the decision is to publish, be very careful about tone.

“They’re real people,” Wood said of such suspects, “and their life as they’ve known it ceases to exist. What is said about them is devastating.”

WASHINGTON — Federal Bureau of Investigation officials on Monday laid out their most detailed scientific case to date against Bruce E. Ivins, the military scientist accused of being the anthrax killer, but they acknowledged that the many mysteries of the case meant an air of uncertainty would always surround it.

“I don’t think we’re ever going to put the suspicions to bed,” said Vahid Majidi, head of the F.B.I.’s weapons of mass destruction division. “There’s always going to be a spore on a grassy knoll.”

At a two-hour briefing for reporters, Dr. Majidi was joined by seven other leading scientists from inside and outside the bureau. They discussed in intricate detail the halting scientific path that led them from two main samples of anthrax used in the 2001 attacks, to four genetic mutations unique to the samples, to 100 scientists in the United States who had access to that particular strain, and ultimately to Dr. Ivins.

Dr. Ivins, a longtime anthrax researcher at the Army Medical Research Institute of Infectious Diseases at Fort Detrick in Maryland, killed himself last month as the Justice Department was preparing an indictment against him. Since his death, a number of scientists have said that the limited forensic evidence that the F.B.I. made public in linking the attacks to Dr. Ivins is inconclusive.

The unusual presentation by the bureau on Monday was intended to quell those doubts, but some scientists remained skeptical. They said it would be months before they were able to evaluate fully the strength of the forensic evidence, and the new process used, in an independent setting.

At the briefing, F.B.I. officials disclosed that they first obtained a sample of a unique strain of anthrax from Dr. Ivins in 2002, one that could have led them back to the strain used in the 2001 attacks. But the bureau destroyed the sample because Dr. Ivins did not follow protocol in the way it was submitted, making it more difficult to use in court.

It was not until 2006, after a backup copy of Dr. Ivins’s sample was found by another scientist working with the F.B.I., that the bureau’s scientists realized it was the same strain used in the anthrax mailings. That crucial finding helped confirm other evidence pointing to Dr. Ivins.

“Looking at it in hindsight,” Dr. Majidi said of the misstep in 2002, “we would do things differently today.”

But Dr. Majidi and the other scientists who worked on the case said the new forensic techniques they developed to trace the genetic makeup of the anthrax samples were groundbreaking and could have wider implications for the identification of other harmful agents that could be carried by water or air.

The 2001 mailings, sent to two senators and several prominent media figures, killed five people and sickened 17. F.B.I. officials said on Monday that they were still uncertain of the paths by which some of the victims came into contact with the anthrax.

But they said they believed that the anthrax was naturally fine enough to seep through the envelopes used in the attacks and that mail sorting equipment dispersed it into the air at several postal processing facilities. Two postal workers in Washington, D.C., were among those killed.

Investigators said a number of circumstantial factors, like Dr. Ivins’s unusual nighttime hours at his laboratory in the days before the anthrax letters were mailed, pointed to him as the killer. But the case relied largely on the scientific evidence that officials said had led them back to two one-liter flasks in his lab.

F.B.I. scientists on Monday laid out the development of the new science, known as microbial forensics, that enabled them to match the attack strain to its source.

They also countered a principal scientific criticism of the investigation: that the spores had been weaponized with a special coating and therefore could not have been made by Dr. Ivins because he did not have the necessary equipment. This criticism is based on the presence of silica in the anthrax-laced attack letters. However, the F.B.I. scientists said that the silica had been imported naturally by the anthrax spores from their environment and that there was no evidence of weaponization.

By June 2002, the Institute for Genomic Research had decoded the full DNA of several strains of anthrax, showing that it might be possible to link the attack strain to its source through diagnostic changes in the DNA.

It took another year to identify the four most distinctive of these changes, or mutations. Meanwhile, the F.B.I. collected 1,000 samples of the Ames strain of anthrax, the especially deadly kind used in the attacks, and started to apply its genetic test to them.

The evidence was soon pointing to Fort Detrick as the likely source of the attack strain, and an anomaly then appeared. A second sample submitted by Dr. Ivins later in 2002, which should have carried the Fort Detrick signature, did not, the officials said. This led the F.B.I. to conclude that the second sample he had submitted was falsely labeled.

Eventually, 8 of the 1,000 strains were found to carry the four mutations, and 100 scientists had access to, or were associated with, the strains. All of these scientists were investigated. The “body of evidence,” officials said, pointed to Dr. Ivins.

Richard O. Spertzel, a retired microbiologist who led the United Nations’ biological weapons inspections of Iraq, said he remained skeptical of the bureau’s argument despite the new evidence. “It’s a pretty tenuous argument,” Dr. Spertzel said in an interview, adding that he questioned the bureau’s claim that the powder was less than military grade.

The F.B.I. scientists said they had been able to reverse-engineer the production and properties of the attack spores, producing bacteria that flew into the air with ease. One person could have prepared the attack anthrax in three to seven days, with equipment available at Fort Detrick, a bureau expert said.

The F.B.I. had been unable to reproduce one feature of the attack spores — their high level of silica — but attributed that to natural variability.

Dr. Spertzel said the failure to reproduce the silica content “raises more questions.” But he added that if the F.B.I. was right and “an individual can make that kind of product, just by drying it, we are in deep trouble as a nation and a world.”

Dr. Matthew S. Meselson, a Harvard biologist and expert on biological weapons, said he had a “good impression of the quality of the limited F.B.I. work I have seen,” but that the strength of the bureau’s case could not be assessed until it published its data. Dr. Meselson said he would like to see the data reviewed by an expert committee, perhaps convened by the National Academy of Sciences.

Dr. Martin E. Hugh-Jones, an anthrax expert at Louisiana State University, said the F.B.I. needed to publish more about the anthrax in the flask in Dr. Ivins’s lab, including the percentage of bacteria carrying each of the four genetic markers. The flask contained a mixture of dozens of spore production runs made at Fort Detrick and Dugway Proving Ground in Utah.

The F.B.I. scientists said the new procedures they developed had been reviewed at each stage by some 60 independent scientists who were involved at various stages of the investigation.

William J. Broad contributed reporting from New York.

An F.B.I. briefing on Monday was supposed to bolster the agency’s conclusion that a lone, disturbed bioterrorism scientist was responsible for the 2001 anthrax attacks that killed five people, sickened 17 others and terrified the country. It fell short of its goal.

The F.B.I. spent years pointing a finger at a different suspect. It is not enough for the agency to brush off continuing skepticism. “There’s always going to be a spore on a grassy knoll,” Vahid Majidi, the chief of the agency’s weapons of mass destruction division told reporters.

A group of independent experts needs to look hard at the F.B.I.’s technical analysis and detective work that combined to convince investigators that the mailed anthrax must have come from Dr. Bruce Ivins, a scientist at the Army’s bioterrorism lab in Fort Detrick in Maryland.

The core of the F.B.I.’s case, was the use of new microbial forensic techniques to match the mailed anthrax with anthrax that the agency says was prepared by Dr. Ivins and contained in a flask that he controlled. Experts identified four distinct genetic markers among the anthrax spores in the mailings. They analyzed anthrax samples gathered from laboratories around the world. Ultimately, they concluded that only anthrax batches prepared by Dr. Ivins contained all four mutations.

Perhaps 100 other scientists had access to the same anthrax supply, either at Fort Detrick or another institution that had received a shipment from Fort Detrick, according to the F.B.I. briefers. Standard police work eliminated all other suspects and found circumstantial evidence incriminating Dr. Ivins.

None of this circumstantial evidence has been subjected to close outside scrutiny. Congress should be sure to examine it closely. And given the overriding importance of the laboratory work in tracing the anthrax to Dr. Ivins’s batches, it is distressing that the F.B.I. has not released more details from its scientific investigation so that independent experts can evaluate it.

From the available information it looks as if the F.B.I. has pulled off a scientific coup. But at least one bioweapons expert has publicly expressed doubt that Dr. Ivins did it, and many of his Fort Detrick colleagues reportedly feel the same. Now that Dr. Ivins’s suicide has precluded a court trial, there needs to be an independent evaluation of whether the F.B.I. has found the right man. For that, the ever-secretive agency is going to have to share more information.

When the Federal Bureau of Investigation announced it had cracked the long-unsolved anthrax case, the turning point cited by the bureau was its identification of a laboratory flask as the source of the anthrax.

The dots, or in this case more than a thousand separate anthrax samples, were connected with the help of a group of scientists working secretly for some seven years. They succeeded by using a combination of new techniques not even invented in late 2001 when the anthrax-laced letters were sent, and that most old-fashioned attribute of expert scientists and detectives: a trained eye.

Now, in their first interviews, after being released this week from their vows of silence, several scientists explained how they charted a new frontier in microbial forensics, one that could have the same evidentiary power as DNA fingerprinting in criminal cases.

The scientists say they are confident the F.B.I. has identified the source of the anthrax, a flask in the custody of Bruce E. Ivins, whom the F.B.I. considers to have been the perpetrator of the attacks. But almost a hundred other people were known to have had access to cultures from the flask, and the scientists say they have no opinion as to whether Dr. Ivins, who committed suicide last month, was the culprit. Some former colleagues and other experts have questioned whether the government was right in suspecting Dr. Ivins, a researcher at the Army Medical Institute of Infectious Diseases in Fort Detrick, Md. But the technical feat of matching the attack anthrax to its source is itself a gripping tale of scientific detection.

The scientific chase began in late 2001 as the first person to contract anthrax from powder in a letter lay dying in a Florida hospital. The victim, Robert Stevens, 63, a photo editor at The Sun, a tabloid, was suffering from pulmonary anthrax, and the F.B.I. needed to know whether the anthrax in the attacks, which began a week after Sept. 11, was natural, or a biological weapon.

A sample of anthrax from Mr. Stevens’s body was flown to Paul Keim, a biologist at Northern Arizona University who two years earlier had developed a test for distinguishing the various strains of anthrax found in nature and in biological weapons laboratories. Of the anthrax strains used as weapons, the most virulent was one known as the Ames strain.

Dr. Keim confirmed the fears of intelligence agencies: it was the Ames strain that infected and eventually killed Mr. Stevens.

Dr. Keim’s test could tell two strains of anthrax apart but it could not tell the bureau what it needed to know next, which of the many cultures of Ames anthrax around the world the attack anthrax might have come from.

The F.B.I. decided to go back to basics and to try decoding the entire DNA sequence — some five million units — of the anthrax genome to see if some clues to its source might be developed. For this job it turned to the Institute for Genomic Research or TIGR, a leader in decoding the genomes of microbes. Its director was then Claire Fraser-Liggett, who is now at the University of Maryland. The F.B.I. asked her to form a group, with as few people as possible, to decode an anthrax genome, without telling her it was the one that had killed Mr. Stevens.

In contrast to the way science is usually done, the research overseen by the F.B.I., which took seven years to finish, was highly compartmentalized. The scientists, who work at academic institutions, say they did not understand important details of the case until a news conference on Monday — which they and their scientific directors in the F.B.I. attended.

For the bureau, the compartmentalization was an essential safeguard against the nightmare that one of their many advisers might turn out to have prepared the attack anthrax. “It may have been in people’s minds that someone in the room could have been one of the perpetrators, which ended up being the case,” said Dr. Chris Hassell, the F.B.I. laboratory director.

By early 2002, the TIGR team had completed the genome and were able to compare it with a culture of Ames anthrax maintained at Porton Down, the British biological weapons establishment. Anthrax is a highly stable organism that changes very little from one generation to another. But the scientists found several differences between the Stevens and Porton Down genomes, raising the possibility that the source of the attack strain might be distinguishable from other cultures of Ames anthrax.

“The finding was very good news for the investigation by giving hope that molecular forensics might bear fruit but, if so, large numbers of samples would need to be analyzed,” Dr. Fraser-Liggett said.

All Ames anthrax is derived from a cow that died in Texas in April 1981. The F.B.I. acquired a sample from Fort Detrick of the original strain, known as the Ames ancestor. Decoding began on that, with the idea of constructing a genealogy that would show the Ames ancestor begat the source culture which begat the attack strain.

The TIGR team decoded the Ames ancestor and then turned to decoding the anthrax from one of the attack mailings. Each decoding took three to four months and cost about $250,000, said Jacques Ravel, a leading member of the TIGR team who is also now at the University of Maryland.

But when the decoding of the attack genome was finished in 2002, the TIGR scientists had a major surprise and disappointment. In virtually all of its five billion units, the attack anthrax was identical to the Ames ancestor. There were no differences that could tie the attack strain to any of the many known cultures of Ames held in laboratories around the world.

At the regular meetings the TIGR scientists held with the F.B.I., they received very little information or feedback. But they could tell that their counterpart scientists in the bureau were as discouraged as they were, Dr. Fraser-Liggett said. Anthrax genomes looked like a dead end.

Then an Army microbiologist from Fort Detrick made an unexpected discovery. Using an old-fashioned microbiological technique, he spread out some attack spores on a bed of nutrient and let each form its own colony. All the colonies looked identical except one, which, to his trained eye, seemed very slightly different. Different-looking colonies are called morphotypes or just “morphs.”

“Had that task been assigned to someone less experienced, these morphotypes might never have been seen or their significance never realized,” Dr. Fraser-Liggett said.

Because of the obvious possibility that the morph might look different because its genome was different, the F.B.I. asked the TIGR team to decode its genome. Four months later, the TIGR scientists were elated when they discovered the morph had a major genetic change in its genome, known as an indel, short for insertion or deletion of DNA. “We were extremely excited,” Dr. Fraser-Liggett said.

With the morph, the attack strain was at last developing a genetic signature of its own. Though 99 percent of its spores were identical with the Ames ancestor, some 1 percent or less were morphs.

Dr. Ravel was asked to decode seven more morph genomes, a task that took two years. He could do only one at a time for fear of cross-contamination in his laboratory. Dr. Fraser-Liggett said she did not know why the F.B.I. did not ask other laboratories to share the task and speed up the critical process.

One of the many mysteries the TIGR team had to live with under the bureau’s management was the puzzle of why the attack spores contained as many morphs as they did. At the news conference they learned why, when an F.B.I. scientist explained that the flask in Dr. Ivins’s custody, known as RMR-1029, held the product of 13 production runs of anthrax made at the Army’s Dugway Proving Ground and 22 spore preparations made at Fort Detrick. Some 160 liters of material, the scientist said, had been concentrated into the liter held in the RMR-1029 flask.

The vast number of spores, and the many different culturing procedures, Dr. Keim said, “guarantees you will see these mutants, and when you mix them together you will have a characteristic signature.”

Other scientists chosen by the F.B.I. selected four of the morphs as having the most reliable indels. All the attack letters contained these four morphs as well as the predominant form of Ames ancestor-type spores. The bureau at last had a signature of the attack strain.

Hoping for just this breakthrough, the bureau had been building a repository of Ames anthrax samples, taken under subpoena from laboratories around the world. As the morphs became available, the F.B.I. started testing samples. At first, some had one or two of the morphs. None had three of the morphs.

By late 2005 to 2006 it became clear that just eight of the 1,070 samples collected included all four morphs. And one of the samples was the ancestor of the other seven. The seven samples came from Fort Detrick and one other laboratory in the United States, F.B.I. scientists said at the Monday news conference, held at F.B.I. headquarters.

The source of the seven was a master flask of Ames anthrax known as RMR-1029 which was kept by Dr. Bruce Ivins. “That’s when the genetics caught up with the investigators,” a Department of Justice prosecutor said.

There, the scientific conclusions end. The bureau then began a second phase of the inquiry, that of ascertaining who had access to the flask and its seven descendants. The F.B.I. investigated almost 100 scientists who had had access to cultures from the flask or were in some way associated with them.

At the news conference, it emerged that Dr. Ivins had in fact submitted two samples of RMR-1029, one in February 2002 and a second in April 2002. The second tested negative. The F.B.I. rejected and destroyed the first sample because it had not been prepared according to a strict protocol that the F.B.I. says Dr. Ivins helped in devising.

A duplicate of the first sample was later located in Dr. Keim’s laboratory, where all duplicates were sent, and tested positive. Asked why Dr. Ivins would submit a true sample of his flask in February but a false one in April, the F.BI. scientists said they could not speculate about his motives.

Dr. Keim said he believed the bureau had correctly identified the source of the attack anthrax. “The science on that is pretty solid,” he said. As to whether Dr. Ivins was the perpetrator, Dr. Keim said that only a jury could make that decision. He said Dr. Ivins had been a friend and he faulted the F.B.I. for not having prevented his suicide. “Whether Bruce did it or not I prefer not to think about,” he said.

Dr. Fraser-Liggett said, “I am absolutely convinced the F.B.I. has the right source flask,” but added that she had no opinion as to who the perpetrator might be.

Scott Shane contributed reporting from Washington.

By early 2002, it seemed clear that the United States government was muffing the anthrax investigation. Microbiologists interviewed by the F.B.I. reported that the bureau didn’t fully understand the science involved and had allowed the destruction of anthrax stocks that might have provided comparisons with the spores used in the attacks.

In the spring of 2002, I wrote a series of columns about the anthrax investigation, including some in which I referred to a “Mr. Z” as an example of the flaws in the F.B.I.’s investigation. Some scientists had mentioned him to the F.B.I. early on as a candidate for closer scrutiny, but those trails weren’t initially followed.

Later, after the authorities tipped off television reporters before a raid of his home, Dr. Steven J. Hatfill held a press conference to deny any involvement in the anthrax case. In the process, he confirmed that he was Mr. Z.

The government later named Dr. Hatfill as a “person of interest” in the case, and agents came to trail him constantly. Government officials leaked private information about Dr. Hatfill to reporters and this year paid him a multimillion-dollar settlement as a result.

Then, this month, the government announced that the real culprit was, Bruce Ivins, another scientist who had worked in the United States biodefense program at Fort Detrick, in Frederick, Md. The F.B.I. claims that Dr. Ivins, who killed himself as the investigation closed in on him, was actually the anthrax murderer, and it exonerated Dr. Hatfill.

So, first, I owe an apology to Dr. Hatfill. In retrospect, I was right to prod the F.B.I. and to urge tighter scrutiny of Fort Detrick, but the job of the news media is supposed to be to afflict the comfortable and comfort the afflicted. Instead, I managed to afflict the afflicted.

Dr. Hatfill sued me and The New York Times, along with others in the news media and the Justice Department. His suit against me and The Times was dismissed, yet even if I don’t have a legal obligation, I do feel a moral one to express regret for any added distress from my columns.

That makes this a good moment to look at the larger question of what principles should govern the collision between the public interest in aggressive news coverage and the individual interest in privacy.

Dr. Ivins is a case in point: Some of his friends and family are convinced of his innocence and believe the F.B.I. hounded him to death. And the evidence against him, while interesting, is circumstantial. Shouldn’t a presumption of innocence continue when a person is dead and can no longer defend himself?

So don the mantle of a journalist for a moment and think about how you would handle these three hypothetical cases:

•

You discover that police have seized barrels of chemicals from a group of young foreign men living in town and are questioning them on suspicion of planning to poison the local reservoir. The men’s lawyer pleads with you to write nothing, saying that the matter will be cleared up and that publicity would exacerbate anti-foreign prejudices and make it impossible for them to remain in the community. Do you write about it?

•

You find that police have a new suspect in the JonBenet Ramsey case and are interrogating him repeatedly. A friendly cop lets you peek at the man’s file. The man’s wife calls up frantically to beg you not to go public, saying that an article would set off a media feeding frenzy that would permanently traumatize their three children. Do you break the story about this suspect?

•

You learn that the local high school girls’ basketball coach has been repeatedly accused of sexual misconduct and has left three previous schools under a cloud of suspicion. The school authorities seem paralyzed and are encouraging the teacher to move again before the next school year, but the police have not been involved. The coach says he is leaving the area and probably teaching. He pleads with you to let the matter drop and hints that a scandal might drive him to kill himself. Do you write anything?

My own answers are yes, no and yes. In the first case, the risk to a reservoir is such a serious health concern that it demands coverage. In contrast, the Ramsey case is titillating but doesn’t involve serious public policy concerns (though any cable TV channel would break the story in a heartbeat). In the third case, the school system has failed and news coverage may be the only corrective oversight.

Naturally, it would be important to give the suspects’ points of view and to humanize them by quoting friends. But my own judgment is that while the cost imposed on individuals can be huge, where crucial public interests are at stake, we in the press should be very wary of keeping what we know from the public.

I invite you to comment on this column on my blog, www.nytimes.com/ontheground, and join me on Facebook at www.facebook.com/kristof.

By SCOTT SHANE and ERIC LICHTBLAU
Published: September 6, 2008

WASHINGTON — A month after the F.B.I. declared that an Army scientist was the anthrax killer, leading members of Congress are demanding more information about the seven-year investigation, saying they do not think the bureau has proved its case.

In a letter sent Friday to Robert S. Mueller III, the director of the Federal Bureau of Investigation, Democratic leaders of the House Judiciary Committee said that “important and lingering questions remain that are crucial for you to address, especially since there will never be a trial to examine the facts of the case.”

The scientist, Bruce E. Ivins, committed suicide in July, and Mr. Mueller is likely to face demands for additional answers about the anthrax case when he appears before the House and Senate Judiciary Committees on Sept. 16 and 17.

“My conclusion at this point is that it’s very much an open matter,” Senator Arlen Specter of Pennsylvania, the top Republican on the Senate committee, said of the strength of the case against Dr. Ivins, a microbiologist at the Army’s biodefense laboratory who worked on anthrax vaccines. “There are some very serious questions that have yet to be answered and need to be made public.”

Bureau officials say they are certain they have solved the nation’s first major bioterrorism attack, in which anthrax-laced letters killed five people, after a long and troubled investigation that by several measures was the most complex in the bureau’s history.

But in interviews last week, two dozen bioterrorism experts, veteran investigators and members of Congress expressed doubts about the bureau’s conclusions. Some called for an independent review of the case to reassure the public and assess policies on the handling of dangerous pathogens like anthrax.

Meanwhile, new details of the investigation, revealed in recent interviews, raised questions about when the bureau focused on Dr. Ivins as the likely perpetrator and how solid its evidence was.

In April 2007, after the mailed anthrax was genetically linked to Dr. Ivins’s laboratory and after he was questioned about late-night work in the laboratory before the letters were mailed, prosecutors sent Dr. Ivins a formal letter saying he was “not a target” of the investigation. And only a week before Dr. Ivins died did agents first take a mouth swab to collect a DNA sample, officials said.

Justice Department officials, who said in early August that the investigation was likely to be closed formally within days or weeks, now say it is likely to remain open for three to six more months. In the meantime, agents are continuing to conduct interviews with acquaintances of Dr. Ivins and are examining computers he used, seeking information that could strengthen the case.

But bureau and Justice Department officials insist that the delay, which they say is necessary to tie up loose ends in a complex investigation, reflects no doubts about their ultimate verdict. “People feel just as strongly as they did a month ago that this was the guy,” said a department official who spoke on the condition of anonymity.

Even the strongest skeptics acknowledged that the bureau had raised troubling questions about Dr. Ivins’s mental health and had made a strong scientific case linking the mailed anthrax to a supply in his laboratory.

But they said the bureau’s piecemeal release of information, in search warrant affidavits and in briefings for reporters and Congress, had left significant gaps in the trail that led to Dr. Ivins and had failed to explain how investigators ruled out at least 100 other people who the bureau acknowledged had access to the same flasks of anthrax.

In interviews, F.B.I. officials said they knew their findings would face intense scrutiny after the bureau admitted that for years it had pursued the wrong man, Steven J. Hatfill, whom the government paid $4.6 million in June to settle a lawsuit that accused the government of leaking information about him to the news media.

Officials also acknowledged that they did not have a single, definitive piece of evidence indisputably proving that Dr. Ivins mailed the letters — no confession, no trace of his DNA on the letters, no security camera recording the mailings in Princeton, N.J.

But they said the case consisted of a powerfully persuasive accumulation of incriminating details. Dr. Vahid Majidi, head of the F.B.I.’s weapons of mass destruction directorate, said the accumulation of evidence against Dr. Ivins was overwhelming: his oversight of the anthrax supply, his night hours, his mental problems and his habit of driving to far-off locations at night to mail anonymous packages.

“Who had the means, motive and opportunity?” said John Miller, assistant F.B.I. director for public affairs. “Some potential suspects may have had one, some had two, but on the cumulative scale, Dr. Ivins had many more of these elements than any other potential suspect.”

Mr. Miller said the bureau ultimately planned to release much more information from its investigative files, including notes of F.B.I. interviews with Dr. Ivins and other suspects and witnesses and surveillance logs detailing his movements and actions. But those disclosures, requiring a detailed review to remove private and classified information, are likely to be months away.

Mr. Mueller, the F.B.I. director, is likely to face tough questions at next week’s scheduled oversight hearings, not just about the case against Dr. Ivins but about the prolonged pursuit of Dr. Hatfill. Senator Charles E. Grassley, an Iowa Republican and frequent critic of the bureau, said he was frustrated by the delay in closing the case and answering questions.

“If the case is solved, why isn’t it solved?” Mr. Grassley asked. “It’s all very suspicious, and you wonder whether or not the F.B.I. doesn’t have something to cover up and that they don’t want to come clean.”

Investigators have not reviewed three boxes of papers left by Dr. Ivins marked for the attention of his lawyer, Paul F. Kemp, because the records must first be reviewed to see whether they should be kept confidential under attorney-client privilege, Mr. Kemp said. A government lawyer not involved in the investigation will soon review the papers with Mr. Kemp, who said some might be given to investigators or made public.

What is clear is that the disclosures have not closed the matter.

“They took their shot,” said Representative Rush D. Holt, a Democrat who holds a doctorate in physics and has followed the case closely because the letters were mailed in his New Jersey district. “They hoped and maybe believed that the case they laid out would persuade everyone. I think they’re probably surprised by the level of skepticism.”

Many scientists who have tracked the case, too, have found the evidence less than decisive.

“For a lot of the scientific community, the word would be agnostic,” said Dr. Thomas V. Inglesby, an expert on bioterrorism at the Center for Biosecurity of the University of Pittsburgh Medical Center. “They still don’t feel they have enough information to judge whether the case has been solved.”

Mr. Holt and Dr. Inglesby were among a number of outsiders who said that only an independent review of the investigation and the evidence against Dr. Ivins — either by Congress or a commission like the one that investigated the Sept. 11 attacks — could give the public confidence that the case was over.

Dr. Ralph R. Frerichs, an epidemiologist at the University of California, Los Angeles who has created a Web site detailing the anthrax case, said that such a review was critical to establishing how the lethal powder was made.

“There’s no clarity on the simplest aspect: is this hard to do or easy to do?” Dr. Frerichs said. If the powder could be made with basic laboratory equipment and no sophisticated additives, as the bureau maintains, laboratory security and background checks for workers may have to be tightened, he said.

Skepticism toward the bureau’s case remains especially pronounced among Dr. Ivins’s former colleagues at the Army laboratory at Fort Detrick, Md.

“Despite the F.B.I.’s scientific and circumstantial evidence, I and many of Dr. Ivins’s former colleagues don’t believe he did it and don’t believe the spore preparations were made at Detrick,” said Dr. Gerry Andrews, a microbiologist who worked at the Army laboratory for nine years and was Dr. Ivins’s boss for part of that time.

Laboratory records obtained by The New York Times show that the anthrax supply labeled RMR-1029, which the F.B.I. linked to the attacks, was stored in 1997 not in Dr. Ivins’s laboratory, in Building 1425, but in the adjacent Building 1412. Former colleagues said that its storage in both buildings at different times from 1997 to 2001 might mean that the bureau’s estimate of 100 people with physical access to it was two or three times too low.

Some microbiologists question the time records documenting Dr. Ivins’s night hours, pointing out that one F.B.I. affidavit said he was in the secure part of the laboratory for exactly 2 hours and 15 minutes three nights in a row — an unlikely coincidence that they said raised questions about the accuracy of the records.

Confusion remains about silicon found in the mailed powder. Some F.B.I. critics say it shows that there was a sophisticated additive that might point away from Fort Detrick as a source, but the bureau concluded that it was merely an accident of the way the anthrax was grown.

Dr. Majidi said that many technical details would be cleared up by the papers published by bureau scientists and consultants over the next year or more. “It’s the collective body of evidence that’s really strong,” Dr. Majidi said.

Without witnesses or forensic experts linking the killings directly to Dr. Ivins, the Justice Department’s public case against him relies largely on “opportunity evidence,” said Robert J. Cleary, the lead prosecutor a decade ago in the Unabomber attacks.

“What prosecutors have to do to persuade the public that this was the guy is to show the uniqueness of the strain of anthrax and to eliminate everyone else who had opportunity and access to it.” That, Mr. Cleary said, “is a challenge.”

FREDERICK, Md. — Six weeks after Bruce E. Ivins killed himself, the cremated remains of Mr. Ivins, the Army scientist and anthrax suspect, are stored at a funeral home here, awaiting the outcome of an unusual probate court proceeding.

In a will he wrote last year, a few months before the Federal Bureau of Investigation focused the anthrax letters investigation on him, Dr. Ivins wrote of his wish to be cremated and have his ashes scattered. But fearing that his wife, Diane, and their two children might not honor the request, he came up with a novel way to enforce his demand: threatening to make a bequest to an organization he knew his wife opposed, Planned Parenthood.

“If my remains are not cremated and my ashes are not scattered or spread on the ground, I give to Planned Parenthood of Maryland” $50,000, Dr. Ivins wrote in the will. Court records value the estate at $143,000.

Ms. Ivins is a former president of Frederick County Right to Life, according to F.B.I. records. Bruce Ivins played keyboards at a Catholic church in Frederick and described himself in e-mail messages as “pro-life,” but he was not an anti-abortion activist, said his lawyer, Paul F. Kemp. Ms. Ivins declined to comment, Mr. Kemp said.

The reason for Dr. Ivins’s concern that his wishes might not be followed is unclear. Roman Catholic canon law “earnestly recommends” burial but permits cremation, said Chester Gillis, a theologian at Georgetown University. However, the ashes must be buried in sacred ground and not scattered, Mr. Gillis said.

The will adds another stroke to the portrait that has emerged from F.B.I. records of Dr. Ivins, an anthrax specialist at the Army’s biodefense laboratory at Fort Detrick, in Maryland, as quirky and mentally troubled. The F.B.I. has said he mailed the anthrax letters that killed five people in 2001, though some former colleagues and members of Congress say the case has not been proved.

Ms. Ivins has continued to defend her husband’s innocence, asking the Orphans’ Court of Frederick County to keep paying his lawyers at Venable L.L.P. from his estate to talk to the news media and prepare for possible Congressional hearings “to show he was not the perpetrator of the crimes.” Court papers say that Dr. Ivins paid $102,500 in legal fees before his death and that the estate incurred another $28,276 in fees through Aug. 21.

The will leaves $20,000 each to his children, both 24, with his firearms and ammunition going to his son, Andrew, and his car to his daughter, Amanda.

John W. Nugent, president of Planned Parenthood of Maryland, said that the will had come as “a total surprise” and that his group did not expect to collect the money. “We understand that the Ivins family has not supported Planned Parenthood’s mission,” Mr. Nugent said.

But the will requires that Diane Ivins provide the court with “detailed proof” that Dr. Ivins’s remains were cremated and scattered. Lawyers said the ashes would be scattered after the court advised them on what proof was needed.

Before the F.B.I. concluded that Dr. Ivins was the anthrax killer, it pursued another former scientist at Fort Detrick, Steven J. Hatfill. The government in June paid $4.6 million to settle a lawsuit filed by Dr. Hatfill and last month publicly cleared him.

Dr. Hatfill’s lawyers are seeking to force Toni Locy, a former reporter for USA Today who wrote articles about the anthrax case, to pay Dr. Hatfill’s legal fees. Before the settlement, a judge had found Ms. Locy in contempt of court for refusing to name her sources.

WASHINGTON — The F.B.I. director defended the bureau’s investigation into the 2001 anthrax attacks Tuesday and said he would bring in outside scientists to conduct a review into the evidence that led investigators to conclude that a military scientist in Maryland was behind the deadly mailings.

The remarks by the director, Robert S. Mueller III, came at a hearing of the House Judiciary Committee and were his first public comments on the anthrax case since the suicide of the sole suspect in the attacks, Bruce E. Ivins, in July. But they did little to mollify Democrats on the committee, who accused the bureau of withholding information on the anthrax investigation and other issues.

Representative John Conyers Jr., the Michigan Democrat who leads the committee and wrote the F.B.I. earlier this month with a series of questions on the anthrax case and other matters, told Mr. Mueller in angry tones that he was frustrated by what he described as the slow response and inadequate information.

“How come we can’t get some straight answers on the questions that I write you, I ask you, I give you in person?” Mr. Conyers said.

“You don’t give us anything!” he shouted, calling the testimony from the director a “song-and-dance hearing.”

Mr. Mueller said the F.B.I. had sought to respond to lingering concerns among lawmakers about the way the case had been handled. But he said the bureau was still limited in what it could say because the case remained open — simply to tie up loose ends, the Justice Department has said — and because Dr. Ivins was never charged with the crime.

Mr. Mueller, echoing scientific evidence that the bureau has released, said forensic testing of samples of the anthrax used in the attacks provided “clear identification” linking the strain to a flask in Dr. Ivins’s laboratory at Fort Detrick, Md., where he studied anthrax vaccines.

Some scientific experts have questioned that assertion, however, and have called for an investigation by Congress or an independent commission to review the F.B.I.’s inquiry from start to finish.

Mr. Mueller told the committee that he recognized the importance of the scientific foundation for the bureau’s case against Dr. Ivins. As a result, he said, he recently began discussions with the National Academy of Sciences to have the academy “undertake an independent review of the scientific approach used during the investigation.”

William Kearney, a spokesman for the academy, said it would most likely appoint a committee of experts in different fields to assess the F.B.I.’s work. Reviews generally take 6 to 18 months.

Mr. Mueller also faced severe questioning from Democrats about new investigative guidelines, announced last week by the Justice Department, that will give the bureau authority to use physical surveillance and undercover interviews in terrorism cases without specific evidence of wrongdoing.

Mr. Mueller said the changes, which are to be made final this month, were vital to counterterrorism efforts. But he acknowledged that they would lower the bar for initiating an F.B.I. investigation below the “reasonable suspicion” standard set by the Supreme Court for some police encounters.

Representative Artur Davis, Democrat of Alabama, told Mr. Mueller that he was troubled by the potential for abuse.

“If you lower the standard,” Mr. Davis said, agents are “going to engage in more aggressive conduct.”

Scott Shane contributed reporting.

WASHINGTON — Senator Patrick J. Leahy, chairman of the Senate Judiciary Committee and a target of the anthrax letters of 2001, said Wednesday that he did not believe the F.B.I.’s contention that an Army scientist conducted the attacks alone.

At a hearing of his committee, Mr. Leahy told the F.B.I. director, Robert S. Mueller III, that even if the bureau was right about the involvement of the scientist, Bruce E. Ivins, who killed himself in July before ever being charged, he thought there were accomplices.

“If he is the one who sent the letter, I do not believe in any way, shape or manner that he is the only person involved in this attack on Congress and the American people,” said Mr. Leahy, Democrat of Vermont.

“I believe there are others involved, either as accessories before or accessories after the fact,” he added. “I believe there are others who can be charged with murder.”

Mr. Leahy, who has received special briefings on the investigation because one of the anthrax-laced letters was addressed to him, later declined to elaborate. “Sorry,” said an aide, David Carle, “but he said his piece and does not intend to comment further today.”

Mr. Leahy was one of several senators at the hearing who raised questions about the bureau’s case. But Mr. Mueller said he stood by the conclusion that Dr. Ivins, who worked at the Army biodefense laboratory at Fort Detrick, Md., was solely responsible for the attacks.

Even after the anthrax case is formally closed, a step that officials say is likely in three to six months, “if we receive additional evidence indicating the participation of any additional person, we certainly would pursue that,” Mr. Mueller said.

On Tuesday, Mr. Mueller said he had asked the National Academy of Sciences to convene an expert panel to review the bureau’s scientific work on the case.

But Senator Charles E. Grassley, Republican of Iowa, said Wednesday that he did not think that was adequate. Mr. Grassley said the academy “would only be reviewing the science and not the detective work,” and added, “I believe we need an independent review of both.”

The hearing underscored the challenge the bureau faces in persuading Congress and the public that the case is resolved. In the audience was Steven J. Hatfill, another former Army biodefense scientist, whom the F.B.I. pursued as a suspect for several years before the Justice Department cleared him this summer and paid $4.6 million to settle a lawsuit he had filed against the government.

Dr. Hatfill did not speak. But Senator Grassley asked Mr. Mueller: “Should not the F.B.I. apologize to Dr. Hatfill? Please explain how chasing an innocent man for four years was not a mistake.”

Mr. Mueller replied that investigators had done nothing “inappropriate.” The settlement, he said, was not for scrutinizing Dr. Hatfill but for leaking information about him to the news media. “I abhor those leaks,” he said.

Mr. Leahy pressed Mr. Mueller to say what laboratories in the United States were capable of producing dry powder anthrax like that used in the attacks, specifically asking about the Dugway Proving Ground, an Army center in Utah, and the Battelle Memorial Institute, a government contractor in Ohio, both of which have made such powder in small quantities in the past.

But Mr. Mueller said he could answer the question only in a closed session because the matter involved classified information. The secrecy appeared likely to fuel rumors, circulating on the Internet and denied by the F.B.I., that the attacks had some link to a secret government bioweapons program.

Mr. Mueller, F.B.I. director since just before the terrorist attacks of Sept. 11, 2001, was criticized at the hearing by Mr. Leahy and others for what they described as his record of failing to answer in a timely manner the committee’s questions on a broad range of subjects.

But he was praised for what senators characterized as his courage in resisting some Bush administration counterterrorism tactics, including harsh interrogation methods and elements of the National Security Agency’s domestic surveillance program.

“Against intense and hostile pressure from the highest offices in the land,” said Senator Sheldon Whitehouse, Democrat of Rhode Island, “you stood for the principle that all public offices have public duties and responsibilities.”

WASHINGTON — Congressional critics of the F.B.I.’s anthrax investigation are seeking an independent review of the seven-year inquiry to assess the bureau’s performance and its conclusion that an Army scientist, Bruce E. Ivins, carried out the 2001 attacks alone.

One proposal, in a bill drafted by Representative Rush D. Holt, Democrat of New Jersey, would create a national commission on the anthrax attacks, a scaled-down version of the commission that studied the Sept. 11, 2001, terrorist attacks. Two Republican senators, Arlen Specter of Pennsylvania and Charles E. Grassley of Iowa, said they would not rule out a commission but thought a Congressional investigation or a series of hearings might work.

“Ultimately I may join Congressman Holt on this,” said Mr. Specter, the top Republican on the Judiciary Committee, who served in 1964 as assistant counsel to the Warren Commission on the assassination of President John F. Kennedy. “But first we need to decide whether the Judiciary Committee can do the job.”

Beth Levine, a spokeswoman for Mr. Grassley, said he supported Mr. Holt’s goal but feared a national commission might prove too expensive and time-consuming.

The proposals came a week after the Federal Bureau of Investigation’s director, Robert S. Mueller III, said he had asked the National Academy of Sciences to review the scientific aspects of the investigation. Mr. Holt and the two senators said they thought a review by the academy would be too narrow to resolve the case.

“They’ll give us a scientific analysis of the anthrax,” Mr. Specter said. “I don’t know that they can cover the broad spectrum of the adequacy of the investigation.”

Mr. Holt said that in addition to assessing the bureau’s detective work and management of the investigation, a commission could gauge the bioterrorist threat and consider how attacks might be prevented and how they should be investigated.

Mr. Holt’s draft bill calls for an 11-member commission appointed by the president and Congressional leaders. The commission would have subpoena power, would hold public hearings and would complete its report in no more than 18 months.

An F.B.I. spokesman, Bill Carter, declined to comment on the commission proposal but noted that Mr. Mueller said at a hearing last week that he was “absolutely open to third-party review” on the case.

Days after the July 29 suicide of Dr. Ivins, a microbiologist who worked on anthrax vaccines at the Army’s biodefense laboratory at Fort Detrick, Md., F.B.I. and Justice Department officials said he alone had mailed the anthrax letters, which killed five people.

Since then, colleagues and friends of Dr. Ivins, bioterrorism experts and members of Congress have said they do not believe the evidence the bureau has released proves he did it.

WASHINGTON — A judge unsealed a new batch of court documents in the anthrax case on Wednesday, filling in further details of the bizarre behavior of Bruce E. Ivins, the Army scientist who the F.B.I. has said carried out the letter attacks of 2001.

Last September, according to a sworn statement from an F.B.I. agent, Dr. Ivins sent himself an exuberant e-mail message under the heading “Finally! I know Who mailed the anthrax!” He did not identify the perpetrator but said he was close to assembling the final proof.

“I’m not looking forward to everybody getting dragged through the mud, but at least it will all be over,” Dr. Ivins wrote, adding, “I should have been a private eye!!!!” and signing the message “Bruce.”

The documents do not speculate about his motive, though Dr. Ivins was aware by that time that he was under suspicion and might have believed that his e-mail — he maintained at least eight e-mail addresses — was being monitored.

Dr. Ivins, 62, an anthrax vaccine specialist at Fort Detrick, Md., killed himself with an overdose of medication in July after learning that he was likely to be charged in the death of five people exposed to the anthrax-laced letters. The F.B.I. has said he carried out the attacks alone, but friends, colleagues and lawmakers have said they remain skeptical about the evidence the bureau has made public.

The hundreds of pages of search-warrant affidavits made public on Wednesday, after a request by The New York Times, offer no major disclosures. Rather, the documents, unsealed by Judge Royce C. Lamberth of the Federal District Court here and posted online by the Justice Department, add to a portrait of Dr. Ivins’s eccentric personality and threatening statements as he faced possible murder charges.

For instance, the documents give a fuller account of a group therapy session on July 9 where Dr. Ivins said that he was a suspect in the anthrax investigation and “that he was angry at the investigators, the government and the system in general.”

“He said he was not going to face the death penalty but instead had a plan to kill co-workers and other individuals who had wronged him,” an affidavit by a federal agent said, citing accounts of those present.

A search of Dr. Ivins’s home in Frederick, Md., three days later found ammunition, a bulletproof vest and a homemade body armor plate, the documents say. F.B.I. agents had already taken guns and ammunition from the house in a search the previous November.

In a further development related to the case, an Army document released this week to The Frederick News-Post revealed that Dr. Ivins was placed on administrative leave and barred from all laboratory space at Fort Detrick in March after spilling anthrax on himself and failing to report the incident immediately. Before telling anyone, he walked home and washed and dried his clothes, the report said.

Earlier, after the November search of his home, he had been barred from the most secure laboratories. But until March, he had been allowed to use less secure areas, where, Army officials said Wednesday, he spilled a nonlethal strain of anthrax.

By SCOTT SHANE and ERIC LICHTBLAU
Published: November 25, 2008

WASHINGTON — A federal court on Tuesday unsealed documents that shed new light on why F.B.I. anthrax investigators spent years pursuing the wrong man, Steven J. Hatfill, who was exonerated by the government this year and received a $4.6 million settlement.

Search warrant affidavits said that Dr. Hatfill filled prescriptions for the antibiotic Cipro, the preferred drug for treatment of anthrax, two days before each of the mailings of anthrax-laced letters in September and October 2001. Under questioning by agents for the Federal Bureau of Investigation, he denied taking Cipro at that time, the affidavits said.

The documents report that Dr. Hatfill spoke of serving in a Rhodesian military unit accused of starting an anthrax epidemic in 1979, told an acquaintance that it would take a “Pearl Harbor-type attack” to awaken the United States to the bioterrorist threat and kept an anthrax simulant in his apartment. They said Dr. Hatfill had access to the Ames strain of anthrax used in the attacks while working at the Army biodefense laboratory at Fort Detrick, Md., from 1997 to 1999.

In August, after the suicide of another researcher who worked at the same Army laboratory, Dr. Bruce E. Ivins, the F.B.I. said it had concluded that Dr. Ivins alone had carried out the anthrax attacks, which killed 5 people and sickened 17 others.

The Justice Department then made public search warrant affidavits laying out circumstantial evidence against Dr. Ivins, including symptoms of mental illness, late hours in the laboratory before the mailings and genetic evidence linking the mailed anthrax to a supply in his laboratory. But no definitive evidence has tied Dr. Ivins directly to the letters or to the site of the mailings in Princeton, N.J., and many of his colleagues and friends have said they do not believe he committed the crime.

The Hatfill search warrant material shows how an accumulation of claims from acquaintances can cast an innocent person in a highly suspicious light, said Mark A. Grannis, a lawyer for Dr. Hatfill. As an example of how innocent details can be made to look suspicious, Mr. Grannis said Dr. Hatfill was taking Cipro, a widely prescribed antibiotic, after sinus surgery in 2001.

Search warrants, Mr. Grannis said, often use hearsay and unconfirmed information to convince a judge that a suspect is worthy of further investigation.

“Whether or not it was right for the government to rely on this kind of information to obtain a search warrant in 2002, we know in 2008 that Steven Hatfill had nothing to do with the anthrax attacks,” Mr. Grannis said.

The F.B.I. affidavits were used to obtain a search warrant in August 2002 for Dr. Hatfill’s apartment and a basement storage room in his building in Frederick, Md., as well as his car and a storage locker he rented in Ocala, Fla. The agency had conducted a search with Dr. Hatfill’s permission two months earlier, but it was considered inconclusive.

In searching Dr. Hatfill’s apartment, investigators seized biological equipment, glass laboratory slides, plastic tubing and a gun silencer, among other belongings, the documents say.

Dr. Hatfill was never charged in the anthrax case, but the searches and government leaks identifying him as a leading suspect drew widespread news coverage. He lost a teaching job at Louisiana State University after officials at the Justice Department, which was paying for the courses, objected to his employment. For months, F.B.I. surveillance teams followed Dr. Hatfill every time he left home.

Dr. Hatfill later sued the F.B.I. and the Justice Department for leaking information about him. A separate lawsuit he filed against The New York Times was dismissed and a lawsuit against Vanity Fair magazine was settled.

A version of this article appeared in print on November 26, 2008, on page A23 of the New York edition.

By DAVID STOUT
Published: December 15, 2008

WASHINGTON — The Supreme Court on Monday declined to consider reinstating a lawsuit against The New York Times by a former government scientist who contended that he was defamed by a series of columns about the anthrax mailings of 2001.

Without comment, the justices refused to accept an appeal by the scientist, Steven J. Hatfill, a specialist in biological weapons. The high court’s refusal leaves intact a unanimous ruling in July by the United States Court of Appeals for the Fourth Circuit, in Richmond, Va. That court ruled that a federal trial judge had been correct in granting The Times’ motion to dismiss Dr. Hatfill’s suit.

At issue was a series of columns by Nicholas D. Kristof, who initially wrote about a scientist he identified as Mr. Z, who was the focus of the investigation into the mailings that killed five people while the country was still reeling from the Sept. 11 terrorist attacks.

In August 2002, Mr. Kristof identified Dr. Hatfill as Mr. Z, saying the scientist had come forward and identified himself as the person being written about. Although the federal authorities had deemed the scientist a “person of interest” in the investigation, he was never charged.

In dismissing Dr. Hatfill’s suit, the Fourth Circuit ruled that the trial judge had been correct in finding that Dr. Hatfill was a public figure and as such had to meet an especially high standard to win his suit against The Times. To prevail in a defamation suit, a public figure must demonstrate that a publication acted with “actual malice.” In other words, Dr. Hatfill had to show that The Times knew or suspected that any suggestion that he was guilty was false, but published the damaging material anyhow.

The Justice Department has formally exonerated Dr. Hatfill and agreed to pay him $4.6 million to settle a suit in which the doctor claimed that law enforcement officials improperly leaked information about him.

In August, the federal authorities said they had found overwhelming circumstantial evidence that the anthrax mailer was Bruce E. Ivins, an Army microbiologist at Fort Detrick, Md., who had recently committed suicide.

By SCOTT SHANE
Published: January 3, 2009

FREDERICK, Md. — Inside the Army laboratory at Fort Detrick, the government’s brain for biological defense, Bruce Edwards Ivins paused to memorialize his moment in the spotlight as the anthrax panic of 2001 reached its peak.

Dr. Ivins titled his e-mail message “In the lab” and attached photographs: the gaunt microbiologist bending over Petri dishes of anthrax, and colonies of the deadly bacteria, white commas against blood-red nutrient.

Outside, on that morning of Nov. 14, 2001, five people were dead or dying, a dozen more were sick and fearful thousands were flooding emergency rooms. The postal system was crippled; senators and Supreme Court justices had fled contaminated offices. And the Federal Bureau of Investigation was struggling with a microbe for a murder weapon and a crime scene that stretched from New York to Florida.

But Dr. Ivins was chipper — the anonymous scientist finally at the center of great events. “Hi, all,” he began the e-mail message. “We were taking some photos today of blood agar cultures of the now infamous ‘Ames’ strain of Bacillus anthracis. Here are a few.” He sent the message to those who ordinarily received his corny jokes and dour news commentaries: his wife and two teenage children, former colleagues and high school classmates. He even included an F.B.I. agent working on the case.

Dr. Ivins, who had helped develop an anthrax vaccine to protect American troops, had spent his career waiting for a biological attack. Suddenly, at 55, he was advising the F.B.I. and regaling friends with scary descriptions of the deadly powder, his expertise in demand.

One recipient of his e-mail message, however, a graduate-school colleague, looked at the photograph of Dr. Ivins and leapt to a shocking conclusion.

“I read that e-mail, and I thought, He did it,” the fellow scientist, Nancy Haigwood, said in a recent interview.

Nearly seven years and many millions of dollars later, after an investigation that included both path-breaking science and costly bungling, the F.B.I. concluded that Dr. Haigwood had been right: the anthrax killer had been at the investigators’ side all along. Prosecutors said they believed they had the evidence to prove that Dr. Ivins alone carried out the attacks, but their assertions immediately met with skepticism among some scientists, lawmakers and co-workers of Dr. Ivins.

With the F.B.I. preparing to close the case, The New York Times has taken the deepest look so far at the investigation, speaking to dozens of Dr. Ivins’s colleagues and friends, reading hundreds of his e-mail messages, interviewing former bureau investigators and anthrax experts, reviewing court records, and obtaining, for the first time, police reports on his suicide in July, including a lengthy recorded interview with his wife.

That examination found that unless new evidence were to surface, the enormous public investment in the case would appear to have yielded nothing more persuasive than a strong hunch, based on a pattern of damning circumstances, that Dr. Ivins was the perpetrator.

Focused for years on the wrong man, the bureau missed ample clues that Dr. Ivins deserved a closer look. Only after a change of leadership nearly five years after the attacks did the bureau more fully look into Dr. Ivins’s activities. That delay, and his death, may have put a more definitive outcome out of reach.

Brad Garrett, a respected F.B.I. veteran who helped early in the case before his retirement, said logic and evidence point to Dr. Ivins as the most likely perpetrator.

“Does that absolutely prove he did it? No,” Mr. Garrett said. With no confession and no trial, he said, “you’re going to be left not getting over the top of the mountain.”

The Times review found that the F.B.I. had disproved the assertion, widespread among scientists who believe Dr. Ivins was innocent, that the anthrax might have come from military and intelligence research programs in Utah or Ohio. By 2004, secret scientific testing established that the mailed anthrax had been grown somewhere near Fort Detrick. And anthrax specialists who have not spoken out previously said that, contrary to some skeptics’ claims, Dr. Ivins had the equipment and expertise to make the powder in his laboratory.

F.B.I. agents, moreover, have shown that Dr. Ivins, a church musician and amateur juggler whom colleagues cherished, hid from them a shadow side of mental illness, alcoholism, secret obsessions and hints of violence.

Still, doubts persist. The case will be reviewed this year by the National Academy of Sciences and by Congress. If the F.B.I. is wrong, then a troubled man was hounded to death and the anthrax perpetrator is still at large, as many of Dr. Ivins’s colleagues at Fort Detrick believe. When institute scientists began their own review of the evidence, nervous Army officials ordered the inquiry dropped.

In November, four of Dr. Ivins’s closest co-workers wrote a glowing obituary of their “valued collaborator” for Microbe, the leading microbiology journal. It did not mention the anthrax accusations and was a singular protest by the four scientists against the F.B.I.’s conclusion.

“His colleagues and friends will remember him not only for his dedication to his work,” the obituary said, “but also for his humor, curiosity and great generosity.”

Fearing an Attack

The Sunday night after the Sept. 11 attacks, Dr. D. A. Henderson, who led the global campaign to eradicate smallpox and had long been a lonely Cassandra warning of the bioterrorism threat, was summoned to an emergency meeting with the secretary of health and human services, Tommy Thompson.

Fearing a germ attack, officials had grounded crop dusters. Apocalyptic warnings were all over the news media: one study said 100 kilograms of anthrax released over Washington could kill 1 million to 3 million people.

Now, Dr. Henderson was told, intelligence reports indicated that there might be a second attack by Al Qaeda, most likely biological. Dr. Henderson gave Mr. Thompson and his aides a disturbing tutorial on anthrax and smallpox. As the meeting ended, an aide thanked him.

“I just hope we’re not too late,” Dr. Henderson replied.

Days later came word of the anthrax letters. First, the death of a tabloid photo editor in Florida, Robert Stevens. Then the poison letters mailed to NBC News and The New York Post with notes declaring “Death to America! Death to Israel!”

And finally the letters to Senators Tom Daschle, Democrat of South Dakota, and Patrick J. Leahy, Democrat of Vermont, spewing deadly spores through the postal system and across official Washington.

Whoever had ignited panic with a tablespoon of anthrax powder, officials assumed, would not stop there. Dr. Henderson wondered if the powder came from the tons of anthrax weaponized by the Soviet Union. Some assumed Al Qaeda was behind the letters; others suspected Iraq.

“My fear was that this first mailing was the tip of the iceberg,” said Bill Raub, a senior official at the Health and Human Services Department. “We feared we would be at their mercy.”

Then — nothing. Within days, investigators were piecing together clues pointing to a domestic source.

First, there were the notes. One warned, “We have this anthrax,” and advised the recipients to take penicillin. Al Qaeda, F.B.I. agents reasoned, would hardly reduce the death toll with an alert that might have saved lives.

Then there was the strain of anthrax. Dr. Paul S. Keim, an anthrax geneticist at Northern Arizona University, identified the spores as Ames, a lethal strain most common in United States research. “It was chilling,” Dr. Keim recalled, but also puzzling. “How in the world did Stevens get a lab strain?”

An alternative theory of a possible perpetrator took shape: the bioevangelist. An American obsessed by the bioterrorism threat — maybe a biodefense insider who might gain in pay or prestige from an attack — had decided to alert the nation.

That meant the potential suspects included the very Army scientists now working so closely with the F.B.I. And at the core of that group was Bruce Ivins.

In 21 years at the Army Medical Research Institute of Infectious Diseases, Dr. Ivins supplied Hershey’s Kisses to office visitors and always showed concern when a colleague was ill. He toasted departing colleagues with humorous poems. He livened up parties with his juggling act and led songs from a portable keyboard at his Catholic church.

Colleagues knew Dr. Ivins, whose e-mail Christmas card one year spelled out “Happy Holidays” in anthrax spores, was an oddball, wearing outmoded bellbottoms and lunching on concoctions of tuna, peas and yogurt. But in a place where red tape and petty rivalry often darkened spirits, he was a bright spot.

“He actually thought of other people,” said Melanie Ulrich, who worked with him on an anthrax project and invited him to the house she shared with her husband, Ricky Ulrich, also an Army scientist. “He was fun.”

Arthur O. Anderson, the top ethicist at the institute, bonded with Dr. Ivins in the 1980s over their shared experience of adopting children. After that, every corridor encounter led to a long, probing talk on adoption or the ethical conundrums of biodefense.

Dr. Anderson said Dr. Ivins had relished provocative conversation. “If you didn’t bite at one of his emotionally laden questions, he’d find another way to shock you,” he said.

They often discussed what they considered groundless criticism of the anthrax vaccine Dr. Ivins had helped produce, which some soldiers blamed for their illnesses. “Bruce was thin-skinned,” Dr. Anderson said.

In the emotional days after Sept. 11, friends were not surprised when Dr. Ivins signed up as a Red Cross volunteer. On Sept. 22, 2001 — a date, it would turn out, between the two anthrax mailings — he attended a Red Cross class, Introduction to Disaster Services. He liked the atmosphere, he told friends, and three months later, as the crushing workload created by the anthrax letters began to ease, he applied for more training.

Noting that he worked at the Army institute, he wrote in his December 2001 application, “Perhaps I could help in case of a disaster related to biological agents.”

Odd and Pressing

There was more to Bruce Ivins than his Army colleagues imagined, and Nancy Haigwood knew it.

She met him in 1976 in the biology department at the University of North Carolina, where he was a post-doctoral fellow and she was a graduate student. She found him odd and tried gently to disengage, but he kept in touch, pressing her with questions about her sorority, Kappa Kappa Gamma.

Dr. Ivins’s boss at U.N.C., Dr. Priscilla B. Wyrick, received similar queries about her sorority, Chi Omega. “He’d say, ‘What’s your secret password? What’s your secret handshake?’ ” she recalled. “I thought he was intellectually interested in secret things.”

Dr. Wyrick said she thought of him then as “a goody-two-shoes, aggressive about his science but very sensitive about how he was portrayed by other people.” She kept up a correspondence with him, and after the letter attack, arranged for him to give a talk at her current university, East Tennessee State.

Dr. Haigwood’s experience with Dr. Ivins was not so benign. Outside her home in Maryland in 1982, a vandal spray-painted her sorority’s Greek initials, “KKG,” on her fence, sidewalk and fiancé’s car window. A year later a letter she had not written appeared under her name in The Frederick News-Post, defending Kappa Kappa Gamma and the hazing of recruits. She was certain Dr. Ivins was responsible.

She said she had found Dr. Ivins’s attentions creepy. She never told him her Maryland address, but he found it anyway. Later, in e-mail messages, he mentioned details about her sons that she had not shared with him.

“He damaged my property, he impersonated me and he stalked me,” said Dr. Haigwood, now director of the Oregon National Primate Research Center.

In November 2001, when she got the e-mailed photograph of Dr. Ivins working with anthrax in the laboratory, she noticed that he was not wearing gloves — a safety breach she thought showed an unnerving “hubris.” That fed her hunch that he had sent the deadly letters.

Knowing her suspicion was an extraordinary leap, she kept it to herself. But three months later, the American Society for Microbiology sent an appeal from the F.B.I. to its 40,000 members.

“It is very likely that one or more of you know this individual,” the message said. F.B.I. profilers thought the killer might have made the anthrax during “off-hours in a laboratory.”

Dr. Haigwood called the bureau, and two agents visited her. After that, they called periodically but gave no hint that they had tried to confirm the vandalism and stalking.

Soon after Dr. Haigwood’s call, there was another reason for investigators to scrutinize Dr. Ivins. The Army found that in December 2001 he had secretly swabbed for anthrax spores outside his secure laboratory space.

Suspecting a technician’s desk was contaminated, he later told an Army investigator, he had tested and found a bacillus, the class of bacteria that includes anthrax. He scrubbed the desk with bleach but did not report the spill, though he mentioned it several weeks later to Dr. Anderson, his ethicist friend.

“I had no desire to cry ‘Wolf!’ ” Dr. Ivins wrote to Army investigators in April 2002. “I would have been agitating many people for no real reason.” Yet Dr. Ivins wrote that he could not recall whether he had retested the desk for anthrax after his cleanup, as regulations required.

His conduct was a flagrant violation of biosafety standards. Anthrax spores outside containment areas could endanger anyone who was not vaccinated. When the spill was properly investigated, three strains of anthrax were found outside the laboratory, including the Ames strain on Dr. Ivins’s desk.

By then, too, the bureau had detailed records showing when scientists entered and left the secure laboratories. The documents showed that Dr. Ivins had worked unusually late hours in his laboratory for several nights before each of the anthrax mailings, a pattern that stood out even at an institute where night hours were common.

Yet neither the spill nor the night hours sparked the suspicions of the anthrax investigators. They were intently focused on another suspect.

Focus on Hatfill

Dr. Ivins’s modest bungalow was across the street from Fort Detrick, and he often walked to work. If he did so on June 25, 2002, a sunny Tuesday, he would have noticed the hubbub as he passed by the Detrick Plaza apartments.

F.B.I. agents and postal inspectors trudged in and out of one unit, toting away items for inspection. A horde of reporters milled around nearby; television helicopters circled overhead. It was one of the most heavily publicized searches in the history of criminal investigations.

Dr. Steven J. Hatfill, who had given permission for the search, never imagined this media circus. It was just the beginning of an intrusion into his life by the F.B.I. and the news media that would show just how tantalizing a case could be built against a man the government would, six years later, officially clear.

For months, agents had been growing more focused on Dr. Hatfill, a physician and virologist who had worked from 1997 to 1999 at the Fort Detrick institute.

He had earned a medical degree but had forged his Ph.D. diploma, written an unpublished novel about a covert bioattack on Washington and bragged on his résumé of a “working knowledge” of biowarfare pathogens. In his apartment, agents found a harmless bacteria commonly used as an anthrax simulant and a notebook on anthrax dissemination.

Then there was the timing. One month before the anthrax attacks, the government suspended Dr. Hatfill’s security clearance after questionable results on a polygraph test, and he told friends he expected to be fired from his job as a bioterrorism consultant. Two days before each of the two anthrax mailings, Dr. Hatfill filled a prescription for Cipro, an antibiotic that protected against anthrax.

Could it all be a coincidence? F.B.I. officials did not think so.

Desperate to find something more definitive against Dr. Hatfill, lead investigators — who had to brief the F.B.I. director, Robert S. Mueller III, on their progress every week — ordered round-the-clock surveillance. Meticulous study of tiny brown fibers found stuck to the envelopes led nowhere. Handwriting comparisons proved useless because the perpetrator had printed in block letters. DNA found on the outside of the Leahy anthrax envelope turned out to be inadvertent contamination by a laboratory worker.

Ignoring the grave doubts of some F.B.I. scientists, agents used bloodhounds to try to link the letters by scent to Dr. Hatfill. They sent divers into a pond outside Frederick, and when that did not turn up anything, they drained two ponds hunting for discarded anthrax-making equipment.

Agents were excited when they dredged from the mud a plastic box that they thought might have been a homemade biological “glove box,” built to work safely on dangerous germs. The excitement lasted only until a Fort Detrick scientist with a rural Southern upbringing took one look and recognized what the $20,000-a-day pond-draining had turned up: a turtle trap.

Soon after the pond debacle, Dr. Hatfill began fighting back, filing lawsuits and dragging F.B.I. officials to all-day depositions. But investigators did not want to give up on him as a suspect — in part because overwhelming scientific evidence was tying the mailed anthrax to Fort Detrick.

By early 2004, F.B.I. scientists had discovered that out of 60 domestic and foreign water samples, only water from Frederick, Md., had the same chemical signature as the water used to grow the mailed anthrax.

By late 2005, genetic analysis by top outside experts had matched the spores to a flask of anthrax at the Army institute. Dr. Ivins had custody of the flask, but some agents were still convinced Dr. Hatfill was the culprit.

The science alone could not close the case. “We could get to a lab, to a refrigerator, to a flask,” said Dwight E. Adams, the F.B.I. laboratory director until 2006. “But that didn’t put the letters in anyone’s hand.”

Sudden Interest

Early in 2006, with the investigation largely stalled, Nancy Haigwood heard from two different F.B.I. agents. Four years after she had reported her suspicions of Dr. Ivins, the bureau suddenly seemed interested.

“They said, ‘We need your help,’ ” Dr. Haigwood recalled. She was frustrated by the delay, but when the agents asked her to strike up a new correspondence with Dr. Ivins, she reluctantly complied. “I was afraid of this man,” she said. “I was convinced he had done it, and I was afraid he’d send me an anthrax letter.”

Some agents believed that their bosses were stuck on Dr. Hatfill, and an internal F.B.I. investigation confirmed their complaint. In mid-2006, Mr. Mueller, the F.B.I. director, quietly moved Richard Lambert Jr., who had led the anthrax investigation since 2002, to a new job running the bureau’s office in Knoxville, Tenn. His replacement, Edward Montooth, a veteran of security and intelligence cases who had worked overseas in places from the Balkans to Indonesia, ordered a fresh look at the evidence.

For four years, Dr. Ivins, like others at Fort Detrick, had simultaneously been a trusted F.B.I. technical consultant and a possible suspect. Now the balance was tipping.

As the bureau’s undercover informant, Dr. Haigwood struck up a breezy e-mail correspondence about scientific grants, pets and travel. Dr. Ivins complained about psychological screening and other “rather obnoxious and invasive measures” imposed at Fort Detrick since the anthrax attacks.

“I got so tired of the endless questions that I finally got a lawyer, after almost three dozen interviews,” he wrote in late 2006, referring to interviews by the F.B.I. agents. One session, he said, was “virtually an interrogation.”

In another message, Dr. Ivins complained about feeling “thoroughly beaten down” but said his volunteer work with the Red Cross had provided welcome relief. “The Red Cross is my fraternity/sorority,” he said.

For Dr. Haigwood, the reference carried disturbing overtones, reflecting the old obsession with sororities, and with certain women, that Dr. Ivins had hidden from family and colleagues.

Dr. Ivins still carried resentment from four decades earlier at Lebanon High School in Ohio, where he had been a nerdy, awkward teenager devoted to photography and, even then, to the study of bacteria.

In recent years, said Rick Sams, a pharmacologist who had been among Bruce Ivins’s few school friends, Dr. Ivins “shared with me feelings about how he’d been treated in high school. He was bitter about being excluded.”

When Dr. Sams urged him to attend their 40th class reunion, Dr. Ivins refused. “He said, ‘Why should I go? Look how they treated me,’ ” Dr. Sams said.

The agents learned, in part from Dr. Ivins himself, that he had in his post-college years made uninvited visits to Kappa Kappa Gamma sorority houses at U.N.C., the University of Maryland and West Virginia University, once making off with a sorority’s ritual book and cipher device.

That was more than 20 years ago. But more recently, agents discovered, Dr. Ivins had left a long trail of online postings about Kappa Kappa Gamma. There were inquiries about arcane details of sorority rituals and a bitter editing battle over the KKG entry on Wikipedia.

Dr. Ivins hid behind the online handles he used for his proliferating e-mail addresses — KingBadger, Jimmyflathead, goldenphoenix. Once, on GreekChat.com, he described what he said was a family history of mental illness, calling his mother “an undiagnosed paranoid schizophrenic.”

The agents learned that Dr. Ivins had long maintained a post office box to receive mail without his family’s knowledge and took long walks or drives on sleepless nights. Once, he admitted, he drove all night to Ithaca, N.Y., and back to leave gifts for a young woman who had left her job in his laboratory to attend Cornell University.

The agents also found e-mail messages in which Dr. Ivins confessed to alarming psychiatric problems. During paranoid episodes, he wrote, he felt like “a passenger on a ride.” Even as he worked at his desk, he wrote, “I’m also a few feet away watching me do it.”

Of his group therapy program, he wrote on Sept. 26, 2001, between the two anthrax mailings, “I’m really the only scary one in the group.”

On the face of it, Dr. Ivins’s strange secret life seemed less relevant to the case than Dr. Hatfill’s boasts about his bioweapons expertise. But anthrax was the core of Dr. Ivins’s working life.

“He was in charge of producing large quantities of wet spores for research,” said John W. Ezzell, a Fort Detrick colleague whose anthrax expertise rivaled that of Dr. Ivins. “So if anybody could have produced a lot of spores without arousing suspicion, it was him.”

Though a public debate had raged for years over whether the mailed anthrax had been “weaponized” with sophisticated chemical additives, the F.B.I. had concluded early on that it was not. Dr. Ezzell agreed, as did Jeff Mohr, an expert on anthrax and other pathogens at the Army’s Dugway Proving Ground in Utah.

Without giving an opinion of Dr. Ivins’s guilt or innocence, both Dr. Ezzell and Dr. Mohr said they believed that any experienced microbiologist could have grown and dried the anthrax using equipment Dr. Ivins had in his laboratory. The trickiest step, they said, was producing anthrax with the letters’ high concentration of spores per gram, a skill Dr. Ivins had mastered.

Evidence Problems

But even if Dr. Ivins could have made the anthrax, did he? “It’s been difficult for a lot of us to accept this,” Dr. Ezzell said. “He was a loyal friend. He was a diligent worker.”

The agents were building what they thought was a prosecutable case against Dr. Ivins, but gaping holes remained. No evidence placed him in Princeton, N.J., where the letters were mailed. No receipt showed that he had bought the same type of envelopes. No security camera had caught him photocopying the notes.

Nor, in his e-mail messages and conversations with confidants, could agents find any hint of a confession. One colleague who knew Dr. Ivins well told them, “If Bruce had done this, he never would have been able to keep quiet about it.”

Yet the agents knew he led a compartmentalized life. He went on vacation with his brother, Charles, each year, but Charles had no idea Bruce had a drinking problem for which he had been in residential treatment and Alcoholics Anonymous. Dr. Ivins spent hours in online exchanges about sororities, but his family knew nothing about it.

Some F.B.I. agents were haunted by the Hatfill precedent. Dr. Hatfill, too, was eccentric. He, too, had begun drinking heavily as he came under scrutiny. He, too, had grown depressed and erratic under the F.B.I.’s relentless gaze.

What if Dr. Hatfill had committed suicide in 2002, as friends feared he might? Would the investigators have released their evidence and announced that the perpetrator was dead?

In May 2007, Dr. Ivins — assured by prosecutors that he was not a target of the investigation — testified under oath to a grand jury on two consecutive days. He answered all the questions about anthrax. Only once did he plead his Fifth Amendment right against self-incrimination, when he was asked about his secret interest in sororities.

A Life Coming Apart

Starting with the search of his house on Nov. 1, 2007, Bruce Ivins’s life began to come irrevocably apart. While some agents carted files, computers and guns from the house, others questioned his wife and children, intimating that they knew he was the killer. Fort Detrick officials banned him from working with anthrax. His career was over.

Last March, after drinking the fruit juice and vodka mix that he had come to rely on and adding a big dose of Valium, he passed out and was discovered by his wife, Diane. Despite his denials, she was convinced it was a suicide attempt.

“You know, he’s been incredibly, incredibly stressed, because of the way he’s been hounded by the F.B.I.,” Mrs. Ivins would later tell Frederick police officers in a recorded interview. “They’ve always treated him as if he was guilty, and I just felt that he couldn’t take it anymore.”

Dr. Ivins spent much of the spring in residential alcohol treatment outside Washington and in western Maryland. But when he returned, the F.B.I. agents were still there, watching his house and trailing him around Frederick.

On July 10, Dr. Ivins reached a breaking point. With a strange smile, he told his therapy group that he expected to be charged with five murders and rambled on about killing himself and taking others with him, using his .22-caliber rifle, Glock handgun and bulletproof vest.

Tipped off by the therapist, Frederick police officers removed Dr. Ivins from the Army laboratory that day. He voluntarily checked himself in at the Sheppard Pratt psychiatric hospital in Baltimore.

After a two-week stay, Dr. Ivins was brought home by his wife. She had left a heartfelt note in his bedroom, saying she hoped that he could turn his life around and that they could enjoy life together.

“He didn’t understand that so many people in the treatment program with him had lost their families because of their alcoholism,” Mrs. Ivins later told the police. “So I wanted to write down how I felt because I loved him — you know, I wanted him to come back and get healthy again so we could continue. He was retiring in September, and we were going to travel and enjoy our adult children finally.”

Her note was blunt. “I’m hurt, concerned, confused and angry about your actions the last few weeks,” she wrote. “You tell me you love me but you have been rude and sarcastic and nasty many times when you talk to me. You tell me you aren’t going to get any more guns, then you fill out an online application for a gun license.”

Mrs. Ivins wrote to her husband that he was paying his lawyers a lot of money but ignoring their advice by contacting two former female laboratory assistants he was preoccupied with. He was keeping odd hours, walking the neighborhood late at night and drinking so much caffeine that he was “jumpy and agitated,” she wrote.

But Mrs. Ivins’s note also expressed support. “I had written on the bottom of the paper that I knew he had not been involved in the anthrax letters in any way and I never doubted his innocence,” said the woman who thought she knew him best.

Even as Mrs. Ivins picked up her husband at the Baltimore hospital last July 24, his group therapist, Jean C. Duley, was in a Frederick courtroom, testifying about threats he had left on her answering machine. A judge signed an order at 10:37 a.m. directing Dr. Ivins to stay away from her.

The order would not be necessary. At 12:31 p.m., according to records checked by the Frederick police, Dr. Ivins stopped in at the Giant Eagle grocery store near his house and bought Tylenol PM, acetaminophen and an antihistamine. He bought a few groceries and filled three prescriptions for his psychiatric illness, possibly a sign that he was thinking about the future.

Then, at 1:21 p.m., evidently concerned that he did not have enough medication for the purpose he was contemplating, he bought a second container of Tylenol PM.

Over the next two days, Mrs. Ivins worked her lunchtime shift at a nearby cafe, went for a swim at Fort Detrick and ran her regular Friday bingo game. In and out of the house, she saw that her husband was sleeping but had risen at least a few times, bringing in the mail and eating breakfast.

She did not worry much; depressed, banned from his laboratory, he had been spending many days in bed. And on the back of her note, he had scribbled that he had a terrible headache and was going to rest.

“Please let me sleep,” he wrote. “Please.”

When she found him on the bathroom floor in the middle of a Saturday night, her voice on the 911 tape was calm and methodical: “He’s unconscious. He’s breathing rapidly. He’s clammy.”

She had been through this before. The dispatcher offered to stay on the line until the ambulance arrived. “I’m O.K.,” Mrs. Ivins said.

One Last Message

Bruce Ivins, the connoisseur of secrets, took with him any knowledge he had of the anthrax attacks. But he left one more surprise for his family: a clause in his will intended to enforce his wish to be cremated and have his ashes scattered. If his demands were not met, $50,000 from his estate would go not to the family but to Planned Parenthood of Maryland, whose abortion services Mrs. Ivins abhorred.

It was one last, devious step for a man whose oddities, for many people, made the F.B.I.’s anthrax accusation more plausible.

But like so much about Dr. Ivins, it cut the other way, too. The F.B.I. theorized that Dr. Ivins had sent anthrax letters to Senators Leahy and Daschle because they were pro-choice Catholics, offending his anti-abortion views. Would an anti-abortion absolutist have flirted with a donation to a cause he despised?

On Oct. 6, a lawyer for the Ivins family filed with the Orphans’ Court of Frederick County certification that Planned Parenthood would not receive the money. His ashes, the document said, “were scattered or spread on the ground, as he directed.”

A version of this article appeared in print on January 4, 2009, on page A1 of the New York edition. 

Postscript: February 28, 2009
A front-page article on Jan. 4 about Bruce E. Ivins, the late Army scientist who the Federal Bureau of Investigation says was responsible for the anthrax letter attacks of 2001, reported that F.B.I. scientists had concluded in 2004 that out of 60 domestic and foreign water samples, only water from near Fort Detrick, Md., where Dr. Ivins worked, had the same chemical signature as the water that had been used to grow the mailed anthrax. That information, provided by a former senior law enforcement official who did not want to be named in the article, suggested that the anthrax could not have come from military and intelligence research programs in Utah and Ohio, as some defenders of Dr. Ivins’s innocence had speculated. The F.B.I. declined to answer questions for that article, which said that the evidence against Dr. Ivins was circumstantial and that many of his colleagues believed the F.B.I.’s conclusion was wrong.

On Tuesday at an American Society for Microbiology conference in Baltimore, an F.B.I. scientist, Jason D. Bannan, said the water research ultimately was inconclusive about where the anthrax was grown. An F.B.I. spokeswoman, Ann Todd, said on Wednesday that the bureau “stands by the statements” of Dr. Bannan. The case will be reviewed this year by the National Academy of Sciences.
 

By SOLOMON MOORE
Published: February 4, 2009

Forensic evidence that has helped convict thousands of defendants for nearly a century is often the product of shoddy scientific practices that should be upgraded and standardized, according to accounts of a draft report by the nation’s pre-eminent scientific research group.
The report by the National Academy of Sciences is to be released this month. People who have seen it say it is a sweeping critique of many forensic methods that the police and prosecutors rely on, including fingerprinting, firearms identification and analysis of bite marks, blood spatter, hair and handwriting.

The report says such analyses are often handled by poorly trained technicians who then exaggerate the accuracy of their methods in court. It concludes that Congress should create a federal agency to guarantee the independence of the field, which has been dominated by law enforcement agencies, say forensic professionals, scholars and scientists who have seen review copies of the study. Early reviewers said the report was still subject to change.

The result of a two-year review, the report follows a series of widely publicized crime laboratory failures, including the case of Brandon Mayfield, a lawyer from Portland, Ore., and Muslim convert who was wrongly arrested in the 2004 terrorist train bombing in Madrid that killed 191 people and wounded 2,000.

American examiners matched Mr. Mayfield’s fingerprint to those found at the scene, although Spanish authorities eventually convinced the Federal Bureau of Investigation that its fingerprint identification methods were faulty. Mr. Mayfield was released, and the federal government settled with him for $2 million.

In 2005, Congress asked the National Academy to assess the state of the forensic techniques used in court proceedings. The report’s findings are not binding, but they are expected to be highly influential.

“This is not a judicial ruling; it is not a law,” said Michael J. Saks, a psychology and law professor at Arizona State University who presented fundamental weaknesses in forensic evidence to the academy. “But it will be used by others who will make law or will argue cases.”

Legal experts expect that the report will give ammunition to defense lawyers seeking to discredit forensic procedures and expert witnesses in court. Lawyers could also use the findings in their attempts to overturn convictions based on spurious evidence. Judges are likely to use the findings to raise the bar for admissibility of certain types of forensic evidence and to rein in exaggerated expert testimony.

The report may also drive federal legislation if Congress adopts its recommendations. Senator Richard C. Shelby, Republican of Alabama, who has pushed for forensic reform, said, “My hope is that this report will provide an objective and unbiased perspective of the critical needs of our crime labs.”

Forensics, which developed within law enforcement institutions — and have been mythologized on television shows from “Quincy, M.E.” to “CSI: Miami” — suffers from a lack of independence, the report found.

The report’s most controversial recommendation is the establishment of a federal agency to finance research and training and promote universal standards in forensic science, a discipline that spans anthropology, biology, chemistry, physics, medicine and law. The report also calls for tougher regulation of crime laboratories.

In an effort to mitigate law enforcement opposition to the report, which has already delayed its publication, the draft focuses on scientific shortcomings and policy changes that could improve forensics. It is largely silent on strictly legal issues to avoid overstepping its bounds.

Perhaps the most powerful example of the National Academy’s prior influence on forensic science was a 2004 report discrediting the F.B.I. technique of matching the chemical signatures of lead in bullets at a crime scene to similar bullets possessed by a suspect. As a result, the agency had to notify hundreds of people who potentially had been wrongfully convicted.

In its current draft report, the National Academy wrote that the field suffered from a reliance on outmoded and untested theories by analysts who often have no background in science, statistics or other empirical disciplines.

Although it is not subject to significant criticism in the report, the advent of DNA profiling clearly set the agenda. DNA evidence is presented in less than 10 percent of all violent crimes but has revolutionized the entire science of forensics. While DNA testing has helped to free more than 200 wrongfully convicted people, “DNA was a shock to police culture and created an alternative scientific model, which promoted standardization, transparency and a higher level of precision,” said Paul Giannelli, a forensic science expert at Case Western Reserve University School of Law who presented his research to the National Academy. Enforcement officials, Mr. Giannelli said, “chose to say they never make mistakes, but they have little scientific support, and this report could blow them out of the water.”

Peter J. Neufeld, a co-director of the Innocence Project, a nonprofit group that uses DNA evidence to exonerate the wrongfully convicted, presented to the academy a study of trial transcripts of 137 convictions that were overturned by DNA evidence and found that 60 percent included false or misleading statements regarding blood, hair, bite mark, shoe print, soil, fiber and fingerprint analyses.

The courts have long struggled with the proper role of scientific evidence. In a 1993 landmark decision, Daubert v. Merrell Dow Pharmaceuticals, the Supreme Court held that scientific testimony had to meet an objective standard. Federal courts have occasionally excluded evidence like handwriting and hair analysis.

Donald Kennedy, a Stanford scientist who helped select the report’s authors, said federal law enforcement agencies resented “intervention” of mainstream science — especially the National Academy — in the courts.

He said the National Institute of Justice, a research arm of the Justice Department, tried to derail the forensic study by refusing to finance it and demanding to review the findings before publication. A bipartisan vote in Congress in 2005 broke the impasse with a $1.5 million appropriation.

Mr. Shelby also accused the National Institute of Justice of trying to infiltrate the forensic study panel with lobbyists for private DNA analysis companies, who were seeking to limit the research to DNA studies.

The National Institute of Justice said it would not comment until the report was released. But a preview of potential turf wars played out in the presentations to the National Academy in December 2007. A forensic expert from the Secret Service blasted the F.B.I. for developing questionable techniques “on an ad-hoc basis, without proper research.”

He said the Secret Service wanted the National Academy “to send a message to the entire forensic science community that this type of method development is not acceptable practice.”

Everyone interviewed for this article agreed that the report would be a force of change in the forensics field.

One person who has reviewed the draft and who asked not to be identified because of promises to keep the contents confidential said: “I’m sure that every defense attorney in the country is waiting for this report to come out. There are going to be challenges to fingerprints and firearms evidence and the general lack of empirical grounding. It’s going to be big.”