WASHINGTON – A National Research Council committee asked
to examine the scientific approaches used and conclusions reached
by the Federal Bureau of Investigation during its investigation of
the 2001 Bacillus anthracis mailings has determined that it
is not possible to reach a definitive conclusion about the origins
of the anthrax in letters mailed to New York City and Washington,
D.C., based solely on the available scientific evidence.
Findings of the committee's study include:
- The FBI correctly identified the dominant organism found in the
letters as the Ames strain of B. anthracis.
- Silicon was present in significant amounts in the anthrax used
in the letters. But the committee and FBI agree that there is no
evidence that the silicon had been added as a dispersant to
"weaponize" the anthrax.
- Spores in the mailed letters and in RMR-1029, a flask found at
the U.S. Army Medical Research Institute for Infectious Diseases
(USAMRIID), share a number of genetic similarities consistent with
the FBI finding that the spores in the letters were derived from
RMR-1029. However, the committee found that other possible
explanations for the similarities -- such as independent, parallel
evolution -- were not definitively explored during the
investigation.
- Flask RMR-1029, identified by the U.S. Department of Justice as
the "parent material" for the anthrax in the attack letters, was
not the immediate source of spores used in the letters. As noted by
the FBI, one or more derivative growth steps would have been
required to produce the anthrax in the attack letters. Furthermore,
the contents of the New York and Washington letters had different
physical properties.
- Although the FBI's scientific data provided leads as to the
origin of anthrax spores in the letters, the committee found that
the data did not rule out other possible sources. The committee
recommended that realistic expectations and limitations regarding
the use of forensic science need to be clearly communicated to the
public.
- Further development and validation of methods for analyzing
environmental samples might have benefited this investigation and
will be important in future investigations.
Following a required FBI security review of the committee's
draft report in October 2010, the bureau asked to provide the
committee with additional materials and briefings about its
investigation. From these materials the committee learned more
about the organization and oversight of the scientific
investigation and about the collection and analysis of
environmental samples.
Included in the new materials were results of analyses performed
on environmental samples collected from an overseas site. Those
analyses yielded inconsistent evidence of the Ames strain of B.
anthracis in some samples. The committee recommends further
review of the investigation of overseas environmental samples and
of classified investigations carried out by the FBI and Department
of Justice.
"The committee commends the FBI for reaching out to the
scientific community for assistance early in the anthrax letters
investigation," said Alice P. Gast, chair of the committee and
president of Lehigh University, Bethlehem, Pa. "We believe this
independent review -- done at the FBI's request -- will help
strengthen the law enforcement and national security community's
scientific and analytical capabilities in future
investigations."
Immediately following the 2001 anthrax attacks, there was no
clear organizational structure to assist the FBI in pursuing the
scientific investigation. Over the course of its inquiry, the FBI
worked to develop one. It found and engaged highly qualified
scientists from both the government and private sector to give
expert scientific advice on anthrax and the attacks. The bureau
appropriately decided to establish a repository of the Ames strain
of B. anthracis gathered from laboratories around the world
against which to compare the anthrax used in the 2001 mailings. But
problems with the repository, the committee found, limited the
strength of conclusions that could be made using it.
During the last decade, new "molecular" scientific methods and
insights relevant to this investigation also became available.
"Using tools such as high-throughput, 'next generation' DNA
sequencing could have strengthened or weakened the association
between spores found in the mailed letters and spores from
RMR-1029," said David A. Relman, vice chair of the committee and
Thomas C. and Joan M. Merigan Professor, Stanford University School
of Medicine, Palo Alto, Calif. "Such new technology will be
important to similar investigations in the future."
The Research Council was asked to consider facts and data
surrounding the scientific investigation based on documents and
oral presentations provided by the FBI and others. Judging the
conduct of the law enforcement inquiry was beyond the scope of this
study. The committee was neither asked for nor offers findings on
the possible guilt or innocence of individuals connected with the
2001 B. anthracis mailings. Moreover, authors of this report
did not review classified materials about the case. Thus, they
cannot comment on how classified information may have influenced
the course of the FBI's inquiry, including the scientific
investigation.
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