Did FBI Scientists Identify a Single, Unique Flask?

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We are slowly
getting more information about the FBI’s lack of a case against
Bruce Ivins. When we first learned of his suicide, we were told
that he was the anthrax killer. Period. Then we got a statement
that there was some technology developed by the FBI for the purpose
of this case. Is this why nearly 7 years passed before an arrest
was made?

The full briefing
was still skimpy on the details, and not very convincing. But what
we were told is that the anthrax was traced to a single flask that
was in Bruce Ivins' possession at Ft. Detrick. Then, Science
Magazine reported
on a "close reading" of the four relevant paragraphs in
the 25-page written brief. We now had a better idea of what exactly
this new technology was, although the FBI refused press access to
its staff scientists.

The surviving
anthrax victims were recently
briefed with four hours of "circumstantial," but "compelling,"
evidence. Now the FBI scientists have given a briefing
of their own, and they have given more details about the scientific
evidence. We still haven't heard anything convincing about Ivins'
guilt, but the case is closed. So I guess that's it.

(As an aside,
we learn in this scientific briefing that the mailed anthrax was
not processed with silicon, as originally reported by the FBI.)

Two things
strike me about this forensic evidence. Rather than make you read
this whole column, I'll skip to the good part — these two things
combine to make it clear that the "single flask" evidence
was an exaggeration, to put it kindly.

First, some
background on the new technology. The Ames strain of anthrax is
a naturally-occurring strain of Anthrax that is being used in US
biodefense research. In order to identify a source of the mailed
anthrax and differentiate it from Ames strain anthrax that is found
in the wild or at any of the many labs that also conduct research
on Ames strain anthrax, sophisticated forensic techniques were needed.

Very similar
techniques have been used for things such as The Human Genome Project.
Indeed, the contractor used for the forensics is The Institute for
Genomic Research — a leader in the field of genome sequencing. Ultimately,
as Science Magazine pointed out, the main innovation was
combining the technologies to solve a crime. Science Magazine
also raised some technical questions about the data since they only
had four paragraphs of explanation to work with. I won't re-iterate
those questions here, and focus instead on the question of whether
the data, as they are reported, actually point to a single, unique

The scientists
compared the mailed anthrax to samples of anthrax that are used
in research, specifically, those identified as being the Ames strain.
Each sample of anthrax could be classified as biologically identical
or biologically non-identical to the mailed anthrax based on a sort
of DNA fingerprint. This is because the anthrax bacterium replicates
asexually: a single cell duplicates its DNA and splits into two
new cells which have identical DNA sequences to each other. Thus,
they are biologically identical.

We found out
in the original written brief that the scientists tested more than
1000 samples from labs around the world. This is presumably an exhaustive
sampling of all known samples of Ames strain anthrax.

Problem #1:
They could necessarily only test samples of Ames strain anthrax
that they already knew existed. What if there are samples
of Ames strain anthrax that the scientists did not test because
they did not know they existed? Aside from Saddam's non-existent
WMD anthrax research, I could easily imagine any number of other
governments (including our own) with highly secretive bioweapons
programs hiding this information from the FBI's anthrax investigators.

All the FBI
can say is that the flask in Ivins’ possession is one possible
source. They can’t prove that it is the only source.

Problem #2:
To allay these concerns, the FBI can claim that it is likely that
it is the source since, out of 1000 samples tested, all of the ones
that matched could be traced to Ivins’ flask.

What?! More
than one sample matched?! Yes — a total of 8 samples matched. "B-but,
b-but, they could all be traced to Ivins," stutters the FBI.
We already know that Ivins was not the only person with access to
"his" flask. But now we learn that, in addition to the
100 other people who had access to Ivins’ flask, there are at least
7 other people (and probably many, many more) who had access to
anthrax that is biologically identical to the mailed anthrax. These
7 other samples were not located at AMRIID.

So, although
we were initially told by the FBI-parroting
that sophisticated scientific techniques could uniquely identify
Ivins’ flask as the smoking gun, we learn that even this flimsy
piece of evidence isn’t true: there are 8 known smoking guns and
a theoretically infinite number of unknown smoking guns.

21, 2008

Muratore [send
her mail
] is an Assistant Professor of Chemistry at American
University. She holds a Ph.D. in Molecular and Cell Biology from
UC Berkeley.

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