FBI’s investigation of the 2001 anthrax letter attacks that killed five people in the United States was marred by weak scientific practices and analytical gaps, a report by Congress’s watchdog agency has concluded. The findings, released 19 December, mirror those reached by a similar study conducted in 2011 by the National Academy of Sciences (NAS).
In 2008, FBI concluded that microbiologist Bruce Ivins, who worked for a U.S. Army research laboratory in Maryland, was responsible for the letter attacks. Ivins committed suicide shortly before the FBI released its findings. But the government’s case was largely circumstantial and rested in part on genetic analyses of anthrax spores used in the attacks and in Ivins’s laboratory.
The 2011 NAS review concluded that the science behind the investigation could not rule out the possibility that someone other than Ivins committed the crime. Last week’s study, from the Government Accountability Office (GAO), comes to a similar conclusion. In particular, GAO found that contractors hired by FBI to test and evaluate the anthrax spores relied on poorly designed sampling and statistical methods. “[T]he FBI lacked a comprehensive approach—or framework—that could have ensured standardization of the testing process,” the report states. “As a result, each of the contractors developed their tests differently, and one contractor did not conduct verification testing, a key step in determining whether a test will meet a user's requirements, such as for sensitivity or accuracy.”
FBI also failed to conduct research to “provide a full understanding of the methods and conditions that give rise to genetic mutations used to differentiate between samples of B. anthracis,” the report states. Similarities between the strains used in Ivins’s laboratory and in at least four attack letters were a key element in FBI’s case, but a failure to understand how the bacteria mutate over time could complicate efforts to compare samples. Several government agencies are now sponsoring research aimed at filling this gap, and FBI has taken steps to improve its scientific practices, the report notes.
FBI “needed better science and measurement in order to be more conclusive,” GAO’s chief scientist, Timothy Persons, told The New York Times. “It sounds nitpicky, but that’s important in building up the scientific evidence for an important case.”
The GAO report “confirms what I have often said—that the F.B.I.’s definitive conclusions about the accuracy of their scientific findings in the Amerithrax case are not, in fact, definitive,” Representative Rush Holt (D–NJ), who requested the report in 2010, told the Times. (Holt is retiring this month from Congress and in February will become the CEO of AAAS, publisher of ScienceInsider.)
GAO was careful to note, however, that it “did not review and is not taking a position on the conclusions the FBI reached when it closed its investigation in 2010.”