Original URL: http://www.fas.org/b
A Compilation of Evidence and Comments on the Source of the Mailed Anthrax
Barbara Hatch Rosenberg, Federation of American Scientists
revised December 3, 2001
All the available evidence indicates that the source of the mailed
anthrax, or the information and materials to make it, is a US government
All letter samples contain the same strain of anthrax, corresponding to
the AMES reference strain in the N. Arizona State University database (which
has been used for identification). That Ames sample was obtained from Porton
Down (UK) in the mid-90's (the sample was marked "October 1932"); Porton
had gotten it from Fort Detrick.
A 2000 paper by M. Hugh-Jones, PJ Jackson, P. Keim et al says that the
Ames strain played a central role in the US BW program. Hugh-Jones says
he learned that from David Huxsoll, Former Commander, USAMRIID. He also
says Vollum 1B was the strain stockpiled (at least in the early days of
the US BW program).
The Ames strain is highly virulent and is used now in the US biodefense
program for testing vaccines etc.
The form in the senate letter: fine particles, very narrow size range (1.5-3
microns diameter, typical of the US process), treated so it won't clump
and will float. The weaponization process used was extraordinarily effective.
The extraordinary concentration (one trillion spores per gram) and purity
of the letter anthrax is believed to be characteristic only of material
made by the US process.
A reporter who writes on anthrax vaccine has privately confirmed that four
labs have told him that under the electron microscope the sample looks
just like material obtained by UNSCOM in Iraq. The Iraqi material was spray-dried
BT; it was not milled. Milled samples contain debris and are therefore
distinguishable. It can thus be concluded that the EM observations indicate
that the letter anthrax was not milled. The US process did not use milling.
The US weaponization process is secret-Bill Patrick, its inventor and holder
of five patents on the process, says it involves a COMBINATION of chemicals.
The Armed Forces Institute of Pathology (Washington DC) is studying the
material using an energy dispersive X-ray spectroscope, which can detect
the presence of extremely tiny quantities of chemicals; traces of materials
have been found.
The Senate sample contains an unusual form of silica, a drying agent used
only in the US process. It does not contain bentonite (used by the Iraqis).
At least one other chemical additive, used in the US process, has been
identified in the sample.
All the letters probably contained the same material. The clumping of the
anthrax in the two letters mailed on Sept 18 (to NBC and the NY Post) probably
resulted from the letters getting wet in the course of mail processing
or delivery, according to Army scientists.
A study of genetic drift at certain locations in anthrax has been carried
out at Northern Arizona State University. The results give an idea of how
many times the letter anthrax had replicated, in comparison to the reference
strain-ie, whether it was grown on a very large scale (as in a State program)
or on a very small scale, as would be likely if recently made by a terrorist.
Word has it that the results are consistent with small scale. This suggests
that the anthrax may have been made specifically for the letters.
Analysis of trace contaminants could also indicate the scale/method of
production (ie, liquid medium, in a fermenter, or solid medium, on petri
dishes, a likely method for small-scale preparation).
It has been reported that the complete sequence has been determined for
the genomes of both the anthrax used in the Florida attack and the Ames
reference strain to which it corresponds. This work was done under government
contract by the Institute for Genomic Research, a private non-profit organization.
The results have not been made public but they are in government hands
and there has been no retraction of the oft-repeated statement that the
anthrax matches the Ames reference strain. In addition, the Ames reference
strain may be a mixture of types, as sequencing has revealed to be the
case for another anthrax strain. If so, the proportions of the mixture
may differ from lab to lab and could be used to identify the source.
Senator Bob Graham, Chairman of the Senate Intelligence Committee, said
in late October that investigators can identify with great certainty which
lab produced the anthrax, but it will be a laborious, time-consuming process.
(Chicago Tribune, 27 Oct 01).
INFORMATION REGARDING THE PERPETRATOR
Contrary to early speculation, there are only about twelve laboratories
known to have the Ames reference strain. Of these, no more than half might
have the capability for weaponization by the American process. These include
both government labs and government contractor labs. Excluding those not
in the East (where the letters were mailed on two dates) would lower the
Analysts believe the letters were not written by a Middle-Easterner. The
FBI publicly conjectures that the perpetrator was a lone, male domestic
terrorist, obviously one with a scientific background and lab experience
who could handle hazardous materials.
The perpetrator must have received anthrax vaccine recently (it requires
a yearly booster shot), whether or not he made the material himself, because
filling the letters was a dangerous operation. The vaccine is in short
supply and is not generally accessible. Vaccination records must be available.
The perpetrator appears to be a forensic expert. He has successfully covered
every personal trace.
There was only 1 week between 11 Sept and Sept. 18th, when the first two
letters (and probably a letter, never found, to AMI) were postmarked. This
suggests that the anthrax was already in hand before Sept 11.
Did the perpetrator have advance knowledge of the Sept 11 attacks? Secretary
of Defense Rumsfeld has said that he does not believe al Qaeda was responsible
for the anthrax attack, and other public officials have increasingly indicated
that the perpetrator was probably domestic.
MOST LIKELY HYPOTHESIS
At first, US officials provided miscellaneous bits of information, some
conflicting; then denied some of the earlier information, then clammed
up. They now have a great deal of information that has not been made public.
Under pressure from leaks, they have started a gradual release of information
The US rejected a UN resolution condemning the anthrax attack, on the grounds
that it could have been domestic terrorism.
The Secretary of Health and Human Services said in October that some of
the relevant information is classified, and some is restricted by the FBI.
John Bolton, Under Secretary of State for Arms Control and International
Security, spoke on Nov. 19 at the opening of the five-yearly Review Conference
of the Biological Weapons Convention in Geneva. At a press conference following
his talk, he said "We don't know, as I say in the statement, at the moment,
in a way that we could make public, where the anthrax attacks came
from." This statement, as well as other information, indicates that US
officials do know where the anthrax came from.
The FBI says it is now investigating government and contractor laboratories
possessing the Ames strain and weaponization capabilities.
The perpetrator is an American microbiologist who has access to
recently-weaponized anthrax or to the expertise and materials for making
it, in a US government or contractor lab. He does not live in or near Trenton,
which is a stop on the Amtrak line that runs along the East coast. If he
is smart enough to handle anthrax he is smart enough not to mail it from
his home town. Trenton is probably accessible to him, however.
The anthrax in the letters was made and weaponized in a US government
or contractor lab. It may have been made recently rather than in the US
BW program before Nixon terminated the program in 1969.
Weaponization of dry anthrax after 1972, when the BWC was signed, could
be construed as a violation of the BWC.
The Ames reference strain in the N. Arizona collection, which matches the
letter sample, is probably an early Ames substrain, eg, the one isolated
in 1928. (If, however, the substrain was a later isolate, eg, 1980, that
would prove that the letter anthrax was made after 1972.) Although Vollum
was the main strain stockpiled by the US during WWII, the search undoubtedly
continued for better strains. The US BW program and biodefense program
apparently switched to the Ames reference strain because of its high virulence.
Undoubtedly the confusion about Ames substrains could be cleared up by
USAMRIID, but they have been evasive.
The motive of the perpetrator was not necessarily to kill but to
create public fear, thereby raising the profile of BW. He simply took advantage
of Sept 11 to throw suspicion elsewhere. The letters warned of anthrax
or the need to take antibiotics, making it possible for those who handled
the letters to protect themselves; and it seems unlikely that the perpetrator
would have anticipated that the rough treatment of mail in letter sorters
etc, would force anthrax spores through the pores of the envelopes (which
were taped to keep the anthrax inside) and infect postal workers.
The choice of media as targets seems designed to ensure publicity about
the threat of biological weapons. One can only speculate that the perpetrator
may have wished to push the US government toward retaliatory action against
some enemy, or to attract funding or recognition to some program with which
he is associated.
The US government has known for some time that the anthrax terrorism
was an inside job. They may be reluctant to admit this. They also may not
yet have adequate hard evidence to convict the perpetrator. In opposition
to most of the countries of the world, the US turned down a Protocol to
monitor compliance with the ban on biological weapons last July. Now we
find that the US has been attacked by BW through its own laxity. At the
Review Conference, the US delegation is proposing, as an alternative to
monitoring compliance internationally, a set of national actions for other
countries to take. These include regulating access to dangerous pathogens.
Physician, heal thyself.
Conclusions: A recent report by the GAO, and many recent statements
by experts in the BW field, hold that terrorists are unlikely to be able
to mount a major biological attack without substantial assistance from
a government sponsor. The recent anthrax attack was a minor one but nonetheless
we now see that it was perpetrated with the unwitting assistance of a sophisticated
government program. It is reassuring to know that it was not perpetrated
by a lone terrorist without such support. However it is not reassuring
to know that a secret US program was the source of that support. Secret
threat assessment activities are undermining the intent of the Biological
Weapons Convention and encouraging BW proliferation in other countries,
which in turn may support terrorist attacks on the US.