FBI explains the science behind the anthrax investigation

— -- It wasn't a Redskins game or a Capitol Hill soiree that was the place to be in Washington D.C. last week. It was "an informal, on-the-record roundtable discussion" held by the FBI to discuss the science behind the 2001 mailing of anthrax-containing envelopes that killed five people. The meeting was held to spill scientific, but not investigative, clues from the still-open case.

In late July, anthrax vaccine researcher Bruce Ivins, 62, of the United States Army Medical Research Institute for Infectious Diseases (USAMRIID) in Frederick, Md., committed suicide. FBI investigators revealed that Ivins was a suspect in the anthrax mailings that sent bioterrorism fears nationwide after the toxin was sent to news organizations and the offices of Sen. Pat Leahy (D-Vt.) and Sen. Tom Daschle (D-S.D.)

Earlier this month, the Justice Department released 2007 search warrants that had been issued for Ivins' home and workplace. The warrants linked four mutations in the attack anthrax — a sub-type of the "Ames" strain used in anthrax vaccine experiments — to a collection held in a flask controlled by Ivins from 1997 to 2004.

U.S. Attorney Jeffrey Taylor has called Ivins' flask of anthrax "the murder weapon." Ivins' attorney Paul Kemp says his client was innocent, suggesting that many researchers had access to the flask. "I have nothing but questions," Kemp said via e-mail Monday. "The science, according to many, can only identify a strain of anthrax. If they can identify it, why didn't they act within the last three years to arrest Ivins?"

To address such questions, the FBI invited news organizations to the science roundtable that was held at 2 p.m. on August 18. Several organizations, including USA TODAY, sent a Justice Department and science reporter.

The J. Edgar Hoover FBI Building, the bureau's headquarters, is a concrete colossus squatting along Pennsylvania Avenue between the U.S. Capitol and the White House. Participants in the roundtable discussion passed through a metal detector booth and walked down an interior driveway before turning into an outdoor hallway that led to a large briefing room, dimly-lit, just like in crime movies. A rectangle of tables waited, with place names for the scientists at the head table.

The scientists included Paul Keim of the University of Northern Arizona in Flagstaff, one of the world's leading anthrax sub-type experts; Claire Fraser-Liggett of the University of Maryland in Baltimore, who led efforts to genetically analyze the attack anthrax; and Jacques Ravel of the University of Maryland School of Medicine, who led the efforts to complete the genomes (the complete mapping of genes) of bacteria colony samples derived from the attack anthrax.