Death in the air: Revisiting the 2001 anthrax mailings and the Amerithrax investigation

The FBI’s investigation into the 2001 mailings, labeled Amerithrax, remains a salient fixture on the post-9/11 landscape. Amerithrax was one of the largest and most complex in American history. It involved more than 10,000 witness interviews worldwide, 80 separate searches, and the recovery of more than 6,000 items of potential evidence, including 5,730 environmental samples from 60 site locations. The lessons of the investigation are crucial to understanding not only the U.S. government’s response to the first deadly bioterror attack on American soil, but also the role scientific evidence does — and does not — play in efforts to attribute bioterror attacks to an individual or group. Today, notwithstanding significant advances in bioforensics, the debates that continue to surround the Amerithrax investigation findings, the Syrian regime’s chemical weapons attacks, or the Russian involvement in the Skripal poisonings are all examples of the doubts confronting even the most earnest attribution efforts.

Hurdles facing bioterrorism attribution
The investigation ran from late 2001 through to its eventual closing in February 2010, nearly two years after its principal subject, Dr. Bruce Ivins, committed suicide. The investigation found that Ivins was responsible for mailing the anthrax-laced letters in 2001 based on a combination of factors, including motive, opportunity, history of mental health struggles, access to the anthrax spore source, proximity of the source to the envelopes used to mail the spores, and a consciousness of guilt.

One key lesson of Amerithrax was that the United States lacked the means for accurate attribution of bioterror attacks. Attribution of a biological attack is the result of a process that combines the results of traditional forensics (fingerprints, tool marks, fiber, trace element analysis, etc.), bioforensics (genomic signatures and analytical chemistry), and investigative techniques (interviews, polygraphs, surveillances, telephone taps, etc.), which are particularly relevant in cases involving foreign actors, intelligence methods (human intelligence and signal intelligence collection and analysis).

Bioforensics, as a component of attribution, was born out of the Amerithrax investigation. But bioforensics, also commonly referred to as microbial forensics, is only one element of attribution. Because of the CSI effect” (i.e., a perception resulting from popular television crime shows that laboratory tests can decisively determine guilt), laboratory tests almost certainly have eclipsed other forms of evidence in their influence over juries. In reality, scientific results take a long time to bear fruit and often are not as unambiguous as portrayed in television fiction.

As the Amerithrax investigation began, microbial forensics was in its infancy, and the capabilities were rudimentary compared to current tools. As Dr. Vahid Majidi, former Assistant Director of the FBI’s WMD Directorate, pointed out in his self-published book on Amerithrax, the goal of the investigation was to meet the legal standards, not necessarily the higher standard of scientific proof. Scientific certainty would have been too time-consuming and expensive. The scientific goal of Amerithrax, to paraphrase Majidi, was the good-enough. Dr. Randy Murch, who was involved in establishing the FBI’s microbial forensics efforts in 1996, stated that science will never get all the way to providing attribution, and that’s the way it will always be. Microbial forensics can exclude some possible perpetrators and include a few.

Thus, for all the progress made in the life sciences since 1996, attribution efforts still have a long way to go. No one size fits all the possible universes of possible threat scenarios. Methods remain largely untested in terms of validation and legal acceptance in federal courts. Having not been tested it the courts, questions remain as to whether the methods would meet the Daubert standard, the rule of evidence governing the admissibility of expert witnessestestimony in federal courts. Given that microbial forensics alone is unable to answer the attribution question, attribution must incorporate all the available tools. Majidi stressed that to assign attribution, it was prudent to look at the information from each element independently and, once all the information had been gathered, to bring together the most diagnostic information to arrive at a conclusion. In the end, any attribution effort will be complex, and the results almost certainly will be controversial.

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Cross asks: How far have the fforts to attribute biological attacks come? He says that the ongoing revolution in biotechnology would have had a profound effect on Amerithrax had those capabilities been available back in 2002.

If the investigation were to take place today, advances in genetic sequencing likely would mean that the case would not have rested on an accidental discovery of unique morphologies to point to signature mutations. The timeframe for the genomic analysis of Amerithrax’s B. anthracis repository also would have been sped up significantly. Decker marvels at the tremendous advances in bioforensics given the exponential increase in sequencing speed and capacity along with a corresponding decrease in cost that took place during Amerithrax and in its aftermath. Decker stated that in 2002 he estimated that sequencing the 1981 Ames strain of B. anthracis would cost close to $500 million and that it would take six months  to find an accurate genomic sequence.  Today the cost has fallen to tens of thousands of dollars and the time required to complete the sequencing shortened to weeks rather than months.

However, even with the advances of the biotechnology revolution, it is unlikely that bioforensics today can, on its own, put a smoking gun in the hands of any one individual or group. Absent a claim of responsibility, reliable attribution of attacks — whether for use in a court case or to justify military or diplomatic responses to chemical or biological weapon use overseas — must combine sound science with investigative techniques and/or intelligence sources and methods. A 2018 exercise, CladeX, conducted by the Johns Hopkins University Center for Health Security, demonstrated the critical importance of a claim of responsibility for attribution and highlighted the lack of relevant scientific expertise in American investigative and intelligence agencies.

Given the serious consequences of error, decision-makers almost certainly will set a very high bar for attribution in terms of accuracy, reliability, and credibility. Ambiguities in interpreting scientific findings, as well as the limitations and nuances inherent in intelligence reporting, make it difficult for attribution efforts to meet that high bar. Faulty science combined with incomplete investigative work likely would result in a miscarriage of justice. Likewise, reliance on faulty science in the absence of solid intelligence about chemical or biological weapons use overseas would be disastrous diplomatically and militarily. Attribution, whether before a jury or before the court of international opinion, must be convincing and any action must be defensible.

Although advances in the life sciences are improving the tools available for bioforensics, Amerithrax also demonstrates the limitations of such innovations. Admittedly, bioforensics was in its infancy at the outset of the investigation. A 2017 Government Accounting Office report cites experts as stating that bioforensics at the time of Amerithrax was incapable of detailed characterization and comparative analyses, and whether the scientific findings would have withstood critical scrutiny in the courts is uncertain. Decker points out the scientific challenges facing Amerithrax at its outset, admitting that his job would have been much easier had he possessed today’s tools. He does not address what direction the case would have taken had the unique morphologies in the anthrax letter spores not been identified. Without that discovery of its link to RMR-1029, investigators may not have focused their attention on Ivins until much later, if ever. In that alternate universe, Amerithrax could have plausibly remained centered on its initial person of interest without ever casting serious suspicion on Ivins.

Cross concludes:

Neither a sterile official history nor a journalistic exercise, Decker’s book fills the gap in the history of the Amerithrax investigation. His book is an exemplary insider account of one of the most challenging investigations ever conducted by the FBI, and it raises important questions about the proper place of science in criminal probes. Decker’s story is all the more important given that few, if any, retellings are likely to come forth from individuals with his level of access and dedication to the truth.

Read more in Glenn Cross, “Death in the air: Revisiting the 2001 anthrax mailings and the Amerithrax investigation,” War on the Rocks (16 January 2019)