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Summary
Less than a month after the September 11, 2001, attacks, letters containing
spores of anthrax bacteria (Bacillus anthracis, or B. anthracis) were sent through
the U.S. mail. Between October 4 and November 20, 2001, 22 individuals
developed anthrax; 5 of the cases were fatal.
Although it was initiated as a public health investigation, the investigation
quickly fell under the purview of the Federal Bureau of Investigation (FBI),
when a deliberate act was suspected and letters containing B. anthracis were
discovered in both New York and Washington, D.C., addressed to Tom Brokaw
of NBC News, the New York Post, and U.S. Senators Tom Daschle of South
Dakota and Patrick Leahy of Vermont.
Over the course of its investigation, the FBI devoted 600,000 investiga-
tor work hours to the case and assigned 17 Special Agents to a Task Force,
along with 10 U.S. Postal Inspectors. The investigation spanned six continents;
involved over 10,000 witness interviews, 80 searches, 26,000 email reviews, and
analyses of 4 million megabytes of computer memory; and resulted in the issu-
ance of 5,750 grand jury subpoenas. Additionally, 29 government, university,
and commercial laboratories assisted in conducting the scientific analyses that
were a central aspect of the investigation (U.S. Department of Justice [USDOJ],
2010, p. 4).
During its investigation of the anthrax mailings, the FBI worked with other
federal agencies to coordinate and conduct scientific analyses of the anthrax
letter spore powders, environmental samples, clinical samples, and samples col-
lected from laboratories that might have been the source of the letter-associated
spores. The agency relied on external experts, including some who had previ -
ously developed tests to differentiate among strains of B. anthracis.
In 2008, seven years into the investigation, the FBI asked the National
Research Council (NRC) of the National Academy of Sciences (NAS) to con-
duct an independent review of the scientific approaches used during the inves -
tigation of the 2001 B. anthracis mailings (see Box S-1 for charge). In addition
to informing FBI investigators about possible leads, much of the science used
1
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2 SCIENTIFIC APPROACHES USED TO INVESTIGATE THE ANTHRAX LETTERS
BOX S-1
Charge to the Committee
The NRC was asked by the FBI to conduct an independent review of the scientific
approaches used during the investigation. The official charge to the committee stated:
An ad hoc committee with relevant expertise will evaluate the scientific founda-
tion for the specific techniques used by the FBI to determine whether these
techniques met appropriate standards for scientific reliability and for use in
forensic validation, and whether the FBI reached appropriate scientific con-
clusions from its use of these techniques. In instances where novel scientific
methods were developed for purposes of the FBI investigation itself, the com-
mittee will pay particular attention to whether these methods were appropriately
validated. The committee will review and assess scientific evidence (studies,
results, analyses, reports) considered in connection with the 2001 Bacillus
anthracis mailings. In assessing this body of information, the committee will
limit its inquiry to the scientific approaches, methodologies, and analytical
techniques used during the investigation of the 2001 B. anthracis mailings.
The areas of scientific evidence to be studied by the committee include, but
may not be limited to:
1. genetic studies that led to the identification of potential sources of B.
anthracis recovered from the letters;
2. analyses of four genetic mutations that were found in evidence and
that are unique to a subset of Ames strain cultures collected during the
investigation;
3. chemical and dating studies that examined how, where, and when the
spores may have been grown and what, if any, additional treatments they
were subjected to;
4. studies of the recovery of spores and bacterial DNA from samples col-
lected and tested during the investigation; and
5. the role that cross contamination might have played in the evidence
picture.
The committee will necessarily consider the facts and data surrounding the
investigation of the 2001 Bacillus anthracis mailings, the reliability of the prin-
ciples and methods used by the FBI, and whether the principles and methods
were applied appropriately to the facts. The committee will not, however, under-
take an assessment of the probative value of the scientific evidence in any
specific component of the investigation, prosecution, or civil litigation and will
offer no view on the guilt or innocence of any person(s) in connection with the
2001 B. anthracis mailings, or any other B. anthracis incidents.
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3
SUMMARY
in the investigation formed the basis of a rapidly developing but still nascent
scientific field, called “microbial forensics,” involving a series of laboratory
tests used to determine the genetic identity of a microbial agent used for
nefarious purposes. The development and application of microbial forensics
would become an essential part of the scientific investigation in the hands of
FBI investigators, who would combine it with physicochemical analyses to
narrow their search for the possible origin of the anthrax used in the attacks.
Key scientific questions focused on how, where, and when the material might
have been produced; whether the material in all the evidence collected was
identical; whether the material had been produced in such a manner as to
make it more easily dispersible; whether it had any distinguishing physical or
chemical properties of value in comparison studies; and whether its biological
characteristics could provide leads to its origins.
The committee carried out its work mindful of the need to identify lessons
that could be learned for future investigations in which science might play an
important role.
Under the terms of the NRC contract with the FBI, the committee was
initially provided with two boxes containing approximately 9,000 pages of
materials regarding the scientific investigations undertaken by the FBI and by
external experts contracted by the FBI during the investigation. At the end of
the study an additional 641 pages were provided to the committee. Throughout
the NRC study process, these FBI-provided materials were covered by FOIA
Exemption 7, law enforcement, and were not publicly available. With the
release of this report, as specified in the contract, these documents have been
deposited in the NRC Public Access File.1
In addition to these materials the FBI briefed the committee on several
occasions. Some of these briefings were done in open session, while others were
conducted in closed sessions covered by FOIA Exemption 7. The committee
also heard from a number of other experts.
In conducting its review, the committee was mindful that, while its focus
was on the science involved in the case, the FBI did not ask the committee to
review all of the science that was used in the investigation. For example, the
committee was not charged to consider or evaluate any of the traditional forensic
science methods and techniques used in criminal investigations (e.g., hair, fiber,
fingerprint, or handwriting analysis) (NRC, 2009a) nor did it consider any of
the psychological or behavioral sciences, such as linguistics, used by the FBI in
its investigation. As such, this report and the committee’s review and evaluation
focused on the application of biological, physical, and chemical sciences to evi-
dentiary materials from the letters, to the collection and analysis of environmental
samples, to the analysis of the flask designated RMR-1029 (a flask containing
1 The public can gain access to these materials by contacting the NRC Public Access Records
Office.
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4 SCIENTIFIC APPROACHES USED TO INVESTIGATE THE ANTHRAX LETTERS
anthrax spores that had been housed and maintained in a U.S. Army Medical
Research Institute of Infectious Diseases [USAMRIID] laboratory at Fort Detrick
since 1997), and to the collection and analysis of the B. anthracis samples from
domestic and international laboratories and stored in the FBI Repository (FBIR).
During the course of the NRC committee’s deliberations, the DOJ
announced on February 19, 2010, that it was closing the case based on its
conclusion that Dr. Bruce Ivins, a scientist at USAMRIID, had alone perpe -
trated the attacks. Dr. Ivins died on July 29, 2008, after taking an overdose of
over-the-counter medications.
FBI SCIENTIFIC CONCLUSIONS AND COMMITTEE FINDINGS
The FBI drew a number of conclusions from its scientific investigation,
which are summarized in Table S-1 at the end of the Summary. The committee
found it challenging, however, to identify a definitive set of scientific conclu -
sions drawn by the FBI investigators because they did not provide them in
written form and because the conclusions provided publicly by DOJ in its brief-
ings and Investigative Summary2 varied from those provided by FBI officials in
presentations to the committee. For the purposes of this report, the committee’s
analyses are based on the scientific conclusions provided by the FBI to the
committee on September 24, 2009 (left-most column of Table S-1) and those
issued publicly by DOJ on February 19, 2010, when it closed the case (USDOJ,
2010) (column second from the left in Table S-1). The committee was not in a
position to offer a judgment about the importance and strength of the evidence
from the scientific investigation relative to the importance and strength of the
evidence from the criminal investigation because it was not charged with (and
lacked the expertise for) reviewing the latter.
A summary of the committee’s findings with regard to the scientific investi -
gation and the scientific conclusions that were drawn from it by the FBI is pro -
vided below. The numbered statements below in bold that are labeled with an
“S” (e.g., S.1) summarize subsets of the committee’s findings and are intended
to organize the findings and help guide the reader through them.
SUMMARY OF COMMITTEE FINDINGS
It is not possible to reach a definitive conclusion about the origins of the
B. anthracis in the mailings based on the available scientific evidence alone.
S.1 The B. anthracis in the letters was the Ames strain and was not genetically
engineered.
2 United States Department of Justice. Amerithrax Investigative Summary. February 19, 2010.
Available at: www.justice.gov/amerithrax/docs/amx-investigative-summary.pdf.
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5
SUMMARY
As background, the Ames strain of B. anthracis was originally isolated
from a dead cow in Texas in 1981 and shipped to USAMRIID in Frederick,
Maryland. Over time it was shared with research and development laboratories
around the world.
• The dominant organism found in the letters was correctly and efficiently
identified as the Ames strain of B. anthracis. The science performed on behalf
of the FBI for the purpose of Bacillus species and B. anthracis strain identifica-
tion was appropriate, properly executed, and reflected the contemporary state
of the art. (Finding 5.13)
• The initial assessment of whether the B. anthracis Ames strain in the
letters had undergone deliberate genetic engineering or modification was timely
and appropriate, though necessarily incomplete. The genome sequences of
the letter isolates that became available later in the investigation strongly sup -
ported the FBI’s conclusion that the attack materials had not been genetically
engineered. (Finding 5.2)
S.2 Multiple distinct colony morphological types, or morphotypes, of B. anthracis
Ames were present in the letters. Molecular assays of specific genetic sequences
associated with these morphotypes provided an approach to determining rela-
tionships among evidentiary samples.
As background, when bacteria are grown on agar plates, the descendants
of single cells produce colonies. Variation in the appearance, or morphology,
of these colonies (i.e., multiple morphotypes) can indicate the presence of
different species or strains in the source material, each with a distinct genetic
signature, or genotype.
• Multiple colony morphotypes of B. anthracis Ames were present in the
material in each of the three letters that were examined (New York Post, Leahy,
and Daschle), and each of the phenotypic morphotypes was found to represent
one or more distinct genotypes. (Finding 5.4)
• Specific molecular assays were developed for some of the B. anthracis
Ames genotypes (those designated A1, A3, D, and E) found in the letters.
These assays provided a useful approach for assessing possible relationships
among the populations of B. anthracis spores in the letters and in samples that
were subsequently collected for the FBIR (see also Chapter 6). However, more
could have been done to determine the performance characteristics of these
assays. In addition, the assays did not measure the relative abundance of the
variant morphotype mutations, which might have been valuable and could be
important in future investigations. (Finding 5.5)
3 The first number in the findings corresponds to the chapter in which they are presented.
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6 SCIENTIFIC APPROACHES USED TO INVESTIGATE THE ANTHRAX LETTERS
• The development and validation of the variant morphotype mutation
assays took a long time and slowed the investigation. The committee recognizes
that the genomic science used to analyze the forensic markers identified in the
colony morphotypes was a large-scale endeavor and required the application of
emerging science and technology. Although the committee lauds and supports
the effort dedicated to the development of well-validated assays and proce -
dures, looking toward the future, these processes need to be more efficient.
(Finding 5.6)
• A distinct Bacillus species, B. subtilis, was a minor constituent of the
New York Post and Brokaw (New York) letters, and the strain found in these
two letters was probably the same. B. subtilis was not present in the Daschle
and Leahy letters. The FBI investigated this constituent of the New York letters
and concluded, and the committee concurs, that the B. subtilis contaminant
did not provide useful forensic information. While this contaminant did not
provide useful forensic information in this case, the committee recognizes that
such biological contaminants could prove to be of forensic value in future cases
and should be investigated to their fullest. (Finding 5.3)
S.3 The FBI created a repository of Ames strain B. anthracis samples and
performed experiments to determine relationships among the letter materials
and the repository samples. The scientific link between the letter material and
flask number RMR-1029 is not as conclusive as stated in the DOJ Investiga -
tive Summary.
• The FBI appropriately decided to establish a repository of samples of
the Ames strain of B. anthracis then held in various laboratories around the
world. The repository samples would be compared with the material found in
the letters to determine whether they might be the source of the letter mate -
rials. However, for a variety of reasons, the repository was not optimal. For
example, the instructions provided in the subpoena issued to laboratories for
preparing samples (i.e., the “subpoena protocol”) were not precise enough to
ensure that the laboratories would follow a consistent procedure for produc -
ing samples that would be most suitable for later comparisons. Such problems
with the repository required additional investigation and limit the strength of
the conclusions that can be drawn from comparisons of these samples and the
letter material. (Finding 6.1)
• The FBI faced a difficult challenge in assembling and annotating the
repository of B. anthracis Ames samples collected for genetic analysis. (Find-
ing 6.9)
• The results of the genetic analyses of the repository samples were con-
sistent with the finding that the spores in the attack letters were derived from
RMR-1029, but the analyses did not definitively demonstrate such a relation -
ship. (Finding 6.2)
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7
SUMMARY
• Some of the mutations identified in the spores of the attack letters and
detected in RMR-1029 might have arisen by parallel evolution rather than by
derivation from RMR-1029. This possible explanation of genetic similarity
between spores in the letters and in RMR-1029 was not rigorously explored
during the course of the investigation, further complicating the interpretation
of the apparent association between the B. anthracis genotypes discovered in
the attack letters and those found in RMR-1029. (Finding 6.3)
• The flask designated RMR-1029 was not the immediate, most proxi-
mate source of the letter material. If the letter material did in fact derive from
RMR-1029, then one or more separate growth steps, using seed material
from RMR-1029 followed by purification, would have been necessary. Further-
more, the evidentiary material in the New York letters had physical properties
that were distinct from those of the material in the Washington, D.C. letters.
(Finding 4.6)
• The genetic evidence that a disputed sample submitted by the suspect
came from a source other than RMR-1029 was weaker than stated in the
Department of Justice Amerithrax Investigative Summary. (Finding 6.4)
• The scientific data generated by and on behalf of the FBI provided leads
as to a possible source of the anthrax spores found in the attack letters, but
these data alone did not rule out other sources. (Finding 6.5)
• Biological material from all four letters should have been examined to
determine whether they each contained all four genetic markers used in screen-
ing the repository samples. (Finding 6.7)
S.4 Silicon was present in the letter powders but there was no evidence of
intentional addition of silicon-based dispersants.
While any deliberate mailing of letters containing anthrax spores might
be considered a form of spore “weaponization,” this term has been more com -
monly used to describe preparations with enhanced properties of dispersion
and aerosolization. It is commonly believed that deliberate efforts to make a
powder more dispersible through the use of additives would suggest a more
sophisticated level of preparation expertise. Thus, the presence of dispersants,
such as nanoparticulate silica or bentonite, was an important feature in consid -
ering whether or not the letters contained “weaponized” anthrax spores.
• Although significant amounts of silicon were found in the powders from
the New York Post, Daschle, and Leahy letters, no silicon was detected on the
outside surface of spores where a dispersant would reside. Instead, significant
amounts of silicon were detected within the spore coat of some samples. The
bulk silicon content in the Leahy letter matched the silicon content per spore
measured by different techniques. For the New York Post letter, however, there
was a substantial difference between the amount of silicon measured in bulk
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8 SCIENTIFIC APPROACHES USED TO INVESTIGATE THE ANTHRAX LETTERS
and that measured in individual spores. No compelling explanation for this
difference was provided to the committee. (Finding 4.3)
• Surrogate preparations of B.anthracis did reproduce physical character-
istics (purity, spore concentration, dispersibility) of the letter samples, but did
not reproduce the large amount of silicon found in the coats of letter sample
spores. (Finding 4.4)
S.5 It is difficult to draw conclusions about the amount of time needed to
prepare the spore material or the skill set required of the perpetrator.
• The committee finds no scientific basis on which to accurately estimate
the amount of time or the specific skill set needed to prepare the spore mate -
rial contained in the letters. The time might vary from as little as 2 to 3 days
to as much as several months. Given uncertainty about the methods used for
preparation of the spore material, the committee could reach no significant
conclusions regarding the skill set of the perpetrator. (Finding 4.1)
S.6 Physicochemical and radiological experiments were properly conducted
to evaluate the samples for potential signatures connecting them to a source
but proved to be of limited forensic value.
• The physicochemical methods used primarily by outside contractors
early in the investigation were conducted properly. (Finding 4.2)
• Radiocarbon dating of the Leahy letter material indicates that it was
produced after 1998. (Finding 4.5)
S.7 There was inconsistent evidence of B. anthracis Ames DNA in environ-
mental samples that were collected from an overseas site. (Finding 3.4)
• At the end of this study, the committee was provided limited infor-
mation for the first time about the analysis of environmental samples for
B. anthracis Ames from an undisclosed overseas site at which a terrorist
group’s anthrax program was allegedly located. This site was investigated by
the FBI and other federal partners as part of the anthrax letters investiga -
tion. The information indicates that there was inconsistent evidence of Ames
strain DNA in some of these samples, but no culturable B. anthracis. The
committee believes that the complete set of data and conclusions concerning
these samples, including all relevant classified documents, deserves a more
thorough scientific review.
S.8 There are other tools, methods, and approaches available today for a sci -
entific investigation like this one.
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9
SUMMARY
• Investigators used reasonable approaches in the early phase of the inves-
tigation to collect clinical and environmental samples and to apply traditional
microbiological methods to their analyses. Yet during subsequent years, the
investigators did not fully exploit molecular methods to identify and character-
ize B. anthracis directly in crime scene environmental samples (without culti-
vation). Molecular methods offer greater sensitivity and breadth of microbial
detection and more precise identification of microbial species and strains than
do culture-based methods. (Finding 3.3)
• Point mutations should have been used in the screening of evidentiary
samples. (Finding 6.6)
• New scientific tools, methods, and insight relevant to this investiga-
tion became available during its later years. An important example is high-
throughput, “next-generation” DNA sequencing. The application of these
tools, methods, and insight might clarify (strengthen or weaken) the inference
of an association between RMR-1029 and the spores in the attack letters. Such
approaches will be important for use in future cases. (Finding 6.8)
• The evidentiary material from this case is and will be immensely valu-
able, especially in the event of future work on either this case or other cases
involving biological terrorism or warfare. It is critically important to continue
to preserve all remaining evidentiary material and samples collected during
the course of this (the anthrax letters investigation) and future investigations,
including overseas environmental samples, for possible additional studies.
(Finding 6.10)
S.9 Organizational structure and oversight are critical aspects of a scientific
investigation. The FBI generated an organizational structure to accommodate
the complexity of this case and received the advice of prominent experts.
• Over the course of the investigation, the FBI found and engaged highly
qualified experts in some areas. It benefited from the unprecedented guidance
of a high-level group of agency directors and leading scientists. The members
of this group had top secret national security clearances, met regularly over
several years in a secure facility, and dealt with classified materials. The NRC
committee authoring this report, in keeping with a commitment to make this
report available to the public, did not see these materials. (Finding 3.1)
• A clear organizational structure and process to oversee the entire scien-
tific investigation was not in place in 2001. In 2003, the FBI created a new orga-
nizational unit (the Chemical, Biological, Radiological, and Nuclear [CBRN]
Sciences Unit, sometimes referred to as the Chemical Biological Science Unit,
or CBSU) devoted to the investigation of chemical, biological, radiological, and
nuclear attacks. The formation of this new unit with clearer lines of authority is
commendable. (Finding 3.2)
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10 SCIENTIFIC APPROACHES USED TO INVESTIGATE THE ANTHRAX LETTERS
• As was done in the anthrax investigation, at the outset of any future
investigation the responsible agencies will be aided by a scientific plan and deci-
sion tree that takes into account the breadth of available physical and chemical
analytical methods. The plan will also need to allow for possible modification
of existing methods and for the development and validation of new methods.
(Finding 3.5)
LOOKING TO THE FUTURE
While much of the committee’s effort was focused on a review of the sci -
ence performed in support of the investigation of the 2001 B. anthracis mail-
ings, an equally important goal has been to help ensure that future scientific
investigations of biological attacks are conducted in the most relevant, rigor-
ous, and thoughtful manner possible. Although the events of 2001 were tragic,
they could have been more catastrophic. In the future, among many other
requirements, it will be important to ensure more timely results, more efficient
environmental analysis, access to globally representative strain collections, and
a robust capability for characterizing less well studied or less easily cultivated
biological agents. Officials may also need to manage expectations among the
general public, policymakers, and the scientific community about the conclu -
sions that can realistically be expected from the use of microbial forensics.
S.10 A review should be conducted of the classified materials that are relevant
to the FBI’s investigation of the 2001 Bacillus anthracis mailings, including all
of the data and material pertaining to the overseas environmental sample col -
lections. (Recommendation 3.1)
The committee did not receive nor review classified material. In November
2010 discussions with FBI and DOJ leadership regarding this report, we were
made aware of additional information that would require review of classified
material. Due to the lateness of this revelation, the importance placed on issu -
ing a timely report, and the agreement between the NRC and the FBI that all
materials we considered be publicly available, the committee did not undertake
this additional review of classified material.
S.11 The goals of forensic science and realistic expectations and limitations
regarding its use in the investigation of a biological attack must be com-
municated to the public and policymakers with as much clarity and detail as
possible before, during, and after the investigation. (Recommendation 3.2)
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11
SUMMARY
TABLE S-1 FBI and DOJ Conclusions and Committee Comments
Relevant
report
finding/
FBI conclusions DOJ conclusions Committee comment section
“Spores of such high The committee finds Finding 4.1
concentration and purity no scientific basis on
indicate that they were which to accurately
derived from high quality estimate the amount of
spore preparations. time or the specific skill
Spores of this quality are set needed to prepare
often used in biodefense the spore material
research, including vaccine contained in the letters.
development. It is important The time might vary
to have highly concentrated from as little as 2 to
spores to challenge most 3 days to as much as
effectively the vaccine being several months. Given
tested. Similarly, highly uncertainty about
purified spores are necessary the methods used for
to prevent obstruction of preparation of the spore
the machinery used in those material, the committee
experiments. These findings could reach no
meant that the anthrax significant conclusions
mailer must have possessed regarding the skill set of
significant technical skill” the perpetrator.
(USDOJ, 2010, p. 14).
continued
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14 SCIENTIFIC APPROACHES USED TO INVESTIGATE THE ANTHRAX LETTERS
TABLE S-1 Continued
Relevant
report
finding/
FBI conclusions DOJ conclusions Committee comment section
Tests led to the “Two separate production The flask designated Finding 4.6
conclusion that batches of anthrax were RMR-1029 was not
two separate used for the New York the immediate, most
production and Washington, D.C., proximate source of the
batches of mailings because each letter material. If the
anthrax were contained differences in letter material did in
used for the spore concentrations, color, fact derive from RMR-
New York and contaminants, texture, 1029, then one or more
Washington, growth media remnants, and separate growth steps,
D.C. mailings observed debris. [But] when using seed material from
because each coupled with the genetic RMR-1029 followed
contained analysis, investigators were by purification, would
differences able to conclude that the two have been necessary.
in spore distinct batches of anthrax Furthermore, the
concentrations, used in the 2001 attacks evidentiary material in
color, shared a common origin” the New York letters
contaminants, (USDOJ, 2010, p. 15). had physical properties
texture, growth that were distinct from
media remnants, those of the material in
and observed the Washington, D.C.
debris. When letters.
coupled with the
genetic analysis
discussed in
Section B, infra,
investigators
were able to
conclude that
the two distinct
batches of
anthrax used in
the 2001 attacks
shared a common
origin (FBI,
2009).
“This strain, known as The dominant organism Finding 5.1
‘Ames,’ was isolated in found in the letters was
Texas in 1981, and then correctly and efficiently
shipped to USAMRIID, identified as the Ames
where it was maintained strain of B. anthracis.
thereafter.”(USDOJ, 2010,
p. 3).
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15
SUMMARY
TABLE S-1 Continued
Relevant
report
finding/
FBI conclusions DOJ conclusions Committee comment section
There was no “The spore particles... The initial assessment Finding 5.2
deliberate genetic showed no signs of genetic of whether the B.
engineering of engineering” (USDOJ, 2010, anthracis Ames strain
the B. anthracis p. 14). in the letters had
strain (FBI, undergone deliberate
2009). genetic engineering or
modification was timely
and appropriate, though
necessarily incomplete.
The genome sequences
of the letter isolates
that became available
later in the investigation
strongly supported the
FBI’s conclusion that
the attack materials had
not been genetically
engineered.
continued
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16 SCIENTIFIC APPROACHES USED TO INVESTIGATE THE ANTHRAX LETTERS
TABLE S-1 Continued
Relevant
report
finding/
FBI conclusions DOJ conclusions Committee comment section
The B. subtilis A distinct Bacillus Finding 5.3
contamination species, B. subtilis, was
found in the a minor constituent of
New York the New York Post and
samples “did Brokaw (New York)
not provide…a letters, and the strain
productive found in these two
avenue in terms letters was probably the
of…leads for the same. B. subtilis was not
investigation” present in the Daschle
(FBI, 2009). and Leahy letters.
The FBI investigated
this constituent of the
New York letters and
concluded, and the
committee concurs,
that the B. subtilis
contaminant did not
provide useful forensic
information. While this
contaminant did not
provide useful forensic
information in this
case, the committee
recognizes that such
biological contaminants
could prove to be of
forensic value in future
cases and should be
investigated to their
fullest.
There were Multiple colony Finding 5.4
mainly wild- morphotypes of
type B. anthracis B. anthracis Ames
Ames strain, were present in the
but there were material in each of
significant the three letters that
numbers of were examined (New
phenotypic York Post, Leahy, and
variants or Daschle), and each
substrains (FBI, of the phenotypic
2009). morphotypes was found
to represent one or
more distinct genotypes.
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17
SUMMARY
TABLE S-1 Continued
Relevant
report
finding/
FBI conclusions DOJ conclusions Committee comment section
These phenotypic “Genetic analysis of Specific molecular Finding 5.5
variants could morphological variants assays were developed
be detected by identified mutations which for some of the
a combination were later exploited to B. anthracis Ames
of assays for develop specific assays genotypes (those
four different to identify the presence designated A1, A3,
insertion/deletion of identical mutations in D, and E) found in
polymorphisms evidence collected during the letters. These
(FBI, 2009). the investigation” (USDOJ, assays provided a
2010, pp. 24-25). useful approach for
assessing possible
relationships among
the populations of B.
anthracis spores in the
letters and in samples
that were subsequently
collected for the FBI
Repository (FBIR) (see
Chapter 6). However,
more could have been
done to determine
the performance
characteristics of these
assays. In addition, the
assays did not measure
the relative abundance
of the variant
morphotype mutations,
which might have been
valuable and could be
important in future
investigations.
There was inconsistent Finding 3.4
evidence of B. anthracis
Ames DNA in
environmental samples
that were collected from
an overseas site.
continued
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18 SCIENTIFIC APPROACHES USED TO INVESTIGATE THE ANTHRAX LETTERS
TABLE S-1 Continued
Relevant
report
finding/
FBI conclusions DOJ conclusions Committee comment section
“…fifteen domestic The FBI repository Section 6.2
laboratories and three was developed from
foreign laboratories were an intensive effort to
identified as repositories of identify laboratories
Ames strain anthrax at the having access to the
time of the letter attacks.” Ames strain; however,
(USDOJ, 2010, p. 17). we cannot conclude that
this approach identified
“…the collection of Ames every laboratory or
isolates from laboratories was a comprehensive
both from the United representation.
States and abroad that
constitute the FBIR
are a comprehensive
representation of the Ames
strain (USDOJ, 2010, p. 28).
“A total of 1, 070 samples
were ultimately submitted
[to the FBIR], which
represents a sample from
every Ames culture at every
laboratory identified by the
FBI as having Ames strain”
(USDOJ, 2010, p. 24).
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19
SUMMARY
TABLE S-1 Continued
Relevant
report
finding/
FBI conclusions DOJ conclusions Committee comment section
“FBI collaborated with The FBI appropriately Finding 6.1
various experts…to provide a decided to establish a
clear and thorough protocol repository of samples
for the preparation of the of the Ames strain of
repository submissions” B. anthracis then held
(USDOJ, 2010, p. 77). in various laboratories
around the world. The
repository samples
would be compared
with the material
found in the letters
to determine whether
they might be the
source of the letter
materials. However,
for a variety of
reasons, the repository
was not optimal.
For example, the
instructions provided
in the subpoena issued
to laboratories for
preparing samples
(i.e., the “subpoena
protocol”) were
not precise enough
to ensure that the
laboratories would
follow a consistent
procedure for
producing samples that
would be most suitable
for later comparisons.
Such problems with
the repository required
additional investigation
and limit the strength
of the conclusions that
can be drawn from
comparisons of these
samples and the letter
material.
continued
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20 SCIENTIFIC APPROACHES USED TO INVESTIGATE THE ANTHRAX LETTERS
TABLE S-1 Continued
Relevant
report
finding/
FBI conclusions DOJ conclusions Committee comment section
“In 2007, after several years The results of the Finding 6.2
of scientific developmens genetic analyses of the
and advanced genetic testing repository samples
coordinated by the FBI were consistent with
Laboratory, the Task Force the finding that the
determined that the spores in spores in the attack
the letters were derived from letters were derived
a single spore-batch of Ames from RMR-1029, but
strain anthrax called “RMR- the analyses did not
1029” (USDOJ, 2010, p. 5.) definitively demonstrate
“Later in the investigation, such a relationship. The
when scientific breakthroughs scientific data alone do
led investigators to conclude not support the strength
that RMR-1029 was the of the government’s
parent material to the repeated assertions that
anthrax powder used in that “RMR-1029 was
the mailings,..” (USDOJ, conclusively identified
2010, p. 6). “After a time- as the parent material
consuming process, the to the anthrax powder
scientific analysis coordinated used in the mailings”
by the FBI Laboratory (USDOJ, 2010, p. 20),
determined that RMR-1029, nor the role suggested
a spore-batch created and for the scientific data
maintained at USAMRIID in arriving at their
by Dr. Ivins, was the parent conclusions, “the
material for the anthrax used scientific analysis
in the mailings.” (USDOJ, coordinated by the FBI
2010, p. 8). ..genetic analysis Laboratory determined
led to the conclusion that that RMR-1029, a
RMR-1029, located at spore-batch created
USAMRIID, was the parent and maintained at
material mailed so the mailed USAMRIID by Dr.
spores,..: (USDOJ, 2010, Ivins, was the parent
p. 16 material for the anthrax
“…based on advanced used in the mailings”
(USDOJ, 2010, p. 8).b
genetic testing combined with
rigorous investigation, the
FBI concluded that RMR-
1029 is the parent material of
the evidentiary anthrax spore
powder, i.e., the evidentiary
material came from a
derivative growth of RMR-
1029” (USDOJ, 2010, p. 28).
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21
SUMMARY
TABLE S-1 Continued
Relevant
report
finding/
FBI conclusions DOJ conclusions Committee comment section
“If Dr. Ivins prepared his The genetic evidence Finding 6.4
submission to the repository that a disputed sample
in accordance with the submitted by the
protocol, that submission suspect came from
could not miss all four of a source other than
the morphological variants RMR-1029 was weaker
present in RMR-1029” than stated in the
(USDOJ, 2010, p. 79). Department of Justice
Amerithrax Investigative
Summary.
“…the only complete genetic The scientific data Finding 6.5
match to the evidence comes generated by and on
from RMR-1029 and its behalf of the FBI
offspring” (USDOJ, 2010, provided leads as to a
p. 29). possible source of the
anthrax spores found in
the attack letters, but
these data alone did not
rule out other sources.
continued
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22 SCIENTIFIC APPROACHES USED TO INVESTIGATE THE ANTHRAX LETTERS
TABLE S-1 Continued
Relevant
report
finding/
FBI conclusions DOJ conclusions Committee comment section
Out of the The FBI and contract Finding 6.1
1,059 viable scientists appropriately discussion
samples from recognized that the
various stocks mutations in the letter
collected in the isolates provided
FBIR during the information that might
investigation, help identify the source
8 contained of the B. anthracis
all 4 of the used in the attacks,
polymorphisms; developed appropriate
2 contained assays for four of
3 of the 4 these mutations, and
polymorphisms; created and screened
and a few a repository of Ames
contained 1 or 2 strain samples. Based
of the mutations. on the results of that
(FBI, 2009). screening, FBI scientists
appropriately concluded
that the majority of
repository samples
contained none of
the four mutations,
although 50 of the
samples contained one
of the four mutations
and 10 samples had
three or all four
mutations (the numbers
with one or more
mutations are higher if
one includes samples
that were excluded in
the FBI’s Statistical
Analysis Report).
However, features of
the repository, including
unknown provenance,
possibly multiple
samples from the same
flask, the history of
sharing and mixing
of stocks presented
investigative challenges.
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23
SUMMARY
TABLE S-1 Continued
aNote that this was the final conclusion of the scientific investigators. An initial finding by the
Armed Forces Institute of Pathology (AFIP) found, upon gross examination, that the spores exhib-
ited a silicon signal and sometimes exhibited an oxygen signal. Subsequent studies conducted by
Sandia National Laboratories (as described in Chapter 4 of this report) determined that the silicon
was localized to the spore coat within the exosporium—that is, it was incorporated into the cell as
a natural part of the cell formation process. The USAMRIID scientist who first reviewed the AFIP
results and made statements regarding the presence of silicon and possible weaponization retracted
those earlier statements.
bSee for example, “As noted above, based on advanced genetic testing combined with rigorous
investigation, the FBI concluded that RMR-1029 is the parent material of the evidentiary anthrax
spore powder, i.e., the evidentiary material came from a derivative growth of RMR-1029.” (p. 28)
“As described in detail above, over time, genetic analysis determined that one of Dr. Ivins’s Ames
cultures, RMR-1029—the purest and most concentrated batch of Ames spores known to exist—was
the parent to the evidentiary material used in the anthrax mailings.” (p.79)
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