WASHINGTON — Scientists behind the case against Bruce E. Ivins, who federal officials allege was solely responsible for the deadly anthrax mailings of 2001, publicly described their work for the first time Monday and said the spores had originated from a flask linked by investigators to the deceased Army scientist.
In two briefings with reporters spanning nearly four hours, the scientists provided new and sometimes clarifying details about the extensive testing that led prosecutors to the brink of filing murder charges against Ivins, who died of a prescription-drug overdose July 29. The briefings were intended to more fully explain the evidence against Ivins and address concerns about the reliability of the government's assertion that Ivins was the culprit.
But Ivins' attorney remained unconvinced, and a top government scientist acknowledged that some skeptics would never be satisfied.
"I don't think we're ever going to put the suspicions to bed," said Vahid Majidi, a chemist and assistant director of the FBI's weapons of mass destruction unit. "There's always going to be a spore on a grassy knoll."
Among the new details Monday was that, contrary to statements made over the years by other government officials, the mailed anthrax had not been coated with additives to "weaponize" it, or make it more deadly. Silicon was detected within the spores, said several of the eight scientists who met with reporters, but it occurred naturally, not as a result of weaponizing.
The silicon did not make the anthrax more buoyant when exposed to air, said James Burans, associate laboratory director of the National Bioforensic Analysis Center.
"The silicon would not have contributed to the fluid-like qualities of the anthrax powders," he said. But loading the powder into envelopes, and their handling by the Postal Service, would have made it more electrostatically charged and difficult to contain, he said.
Burans also said that high-speed mail processing machinery could have crushed the powder more finely -- evidenced by plumes that rose 30 feet above the floor at a postal annex in Washington.
On the other hand, he and the other scientists did not offer an exact explanation of how Ivins was able to prepare the fluffy, dry, powdered anthrax. Ivins, they said, could have used a lab-issue drier called a lyophylizer, but not necessarily.
