The Federal Bureau of Investigation (FBI) will ask the National Academy of Sciences (NAS) to conduct an independent review of the scientific evidence that led the agency to implicate U.S. Army researcher Bruce Ivins in the anthrax letter attacks of 2001. FBI Director Robert Mueller made the announcement today at an oversight hearing held by the House Judiciary Committee where the agency came under fire for failing to provide a clear picture of its 7-year-long investigation into the deadly mailings that killed five people.
FBI officials have been under intense pressure from lawmakers, scientists, and the media to explain how the agency concluded that the attacks were carried out by Ivins, who killed himself on 28 July. Following the suicide, the FBI released court documents laying out some of the evidence linking the anthrax spores found in the letters to Ivins's lab at the U.S. Army Medical Institute for Infectious Disease at Fort Detrick, Maryland. Officials then held a press conference to explain the science that helped identify the unique genetic signature of the mailed anthrax and trace it to a flask under Ivins's control (ScienceNOW, 18 August.) But that did not end calls from many in the scientific community and the general public asking the agency to be more forthcoming.
The agency's decision to have the scientific evidence reviewed independently appears to be a response to that lingering skepticism. At the House Judiciary Committee hearing today, Mueller pointed out that the science behind the case had already undergone vetting by the research community through the involvement of more than 60 nonagency scientists consulted by FBI. Nonetheless, "we are in discussions with NAS to review the work that was done during the investigation," Mueller said. In response to a question by a committee member, he indicated that the review would help resolve confusion over questions such as the source of silicon detected in the anthrax powder, which in the early days of the investigation was ascribed to silica added to make the spores more easily dispersible. At the press conference last month, a Sandia National Laboratory researcher explained that later studies found the silicon to be encapsulated within the spores, indicating that it was naturally occurring and not attributable to a weaponizing additive.
Vahid Majidi, the head of FBI's Weapons of Mass Destruction directorate, told ScienceNOW that he had already held meetings with academy officials. The FBI is currently drafting a document describing the scope of the review that it wants the academy to undertake. "We intend to share all of our scientific evidence with the reviewers," he says.
NAS spokesperson Bill Kearney says as with all studies commissioned to the academy, the request will have to be approved by the NAS governing board before it can go forward. If approval is granted, the review will likely involve two groups within the academy--the Board on Life Sciences and the Committee on Science, Technology, and the Law. Kearney also said the external scientists who had participated in the investigation would be excluded from the committee formed to do the study.
Academics say the review is a welcome step. "While we will never be able to conclude beyond a shadow of a doubt that Dr. Ivins was the perpetrator of the attacks, having a broad scientific hearing on the case will allow for the kinds of questions to be asked that may solidify that conclusion," says bioterrorism expert Michael Osterholm of the University of Minnesota, Minneapolis, who told Science last month that FBI needed to present its case in a scientific court of law convened by an independent body like the NAS.