The Federal Bureau of Investigation (FBI) today unveiled some of the evidence that led the agency to accuse microbiologist Bruce Ivins in the anthrax attacks of 2001, including a pattern of evening visits he made to his lab in the days prior to the strikes. The government released a limited batch of documents as Ivins's lawyer and others suggested that the FBI had hounded the mild-mannered scientist to his death. Ivins, who worked at the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID) in Fort Detrick, Maryland, committed suicide on 29 July as the FBI was preparing to charge him with mailing the letters that killed five people and sickened 17 others in the fall of 2001.
Fourteen search warrants and supporting documents related to the case were posted on the Department of Justice's Web site this afternoon after a federal court in Washington, D.C., granted prosecutors permission to do so. Some details had been blacked out, presumably for privacy concerns.
Although the documents do not include the FBI's full technical analysis, they offer some insight into the bureau's use of bacterial genetic analysis. An affidavit cites the agency's use of "four individual, highly sensitive, and specific molecular assays capable of detecting four of the genetic mutations" discovered in the anthrax that was mailed. These assays were used to study the more than 1000 isolates of the Ames strain--the strain used in the attacks--that the FBI rounded up from 16 U.S. labs, including USAMRIID, and labs in Canada, Sweden, and the United Kingdom.
Of these isolates, "only eight were determined to contain all four genetic mutations" found in the mailed spores. Investigators went on to find that each of these eight isolates was "directly related to a single Bacillus anthracis Ames strain spore batch, identified as RMR-1029," that was stored in "the B3 biocontainment suite within Building 1425" of USAMRIID. "Dr. Bruce Ivins has unrestricted access to the suite and has been the sole custodian of RMR-1029 since it was first grown in 1997," the affidavit says.
The documents do not provide any details about the assays, although they note that the techniques did not become available to the FBI until late in the 6-year investigation. Gregory Koblentz, deputy director of the biodefense program at George Mason University in Fairfax, Virginia, speculates that the FBI may have used a recent technique based on the identification of Single-Nucleotide Repeat markers in the anthrax genome that allows for differentiating between variants of the same strain. Media reports suggest that the FBI was also helped by a technology for high-throughput genetic analysis made available by a California company called Ibis Biosciences.
The evidence includes a bar chart of Ivins's visits to Building 1425 after work hours for 2000 and 2001, showing that he spent unusually long hours in the lab in the days prior to the attacks. The documents also note that Ivins tried to mislead investigators by providing wrong samples. In addition, they cite his mental health problems, dating back to February 2000, as a possible explanation for his actions.
On the whole, the limited information about the scientific analysis used in the investigation has left researchers dissatisfied. "There isn't a lot there, scientifically," says Thomas Geisbert a former USAMRIID researcher now at Boston University. "They don't really get into how they did it." However, he says, some of the information about Ivins's behavior seems "damning."