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US: Ivins solely responsible for anthrax attacks
(Agencies)
Updated: 2008-08-07 11:19

That's not enough, said Grassley, the Iowa senator. He said there should be hearings rather than "the selective release of a few documents."

"This has been one of the largest domestic terrorism investigations in the FBI's 100-year history, and the investigative team made mistakes, missteps and false accusations," he said.

The government material describes at length painstaking scientific efforts to trace the source of the anthrax that was used in the attacks.

It says that in his lab, Ivins had custody of a flask of anthrax termed "the genetic parent" to the powder involved -- a source that investigators say was used to grow spores for the attacks on "at least two separate occasions."

Anthrax culled from the letters was quickly discovered to be the so-called Ames strain of bacteria, but with genetic mutations that made it distinct. Scientists developed more sophisticated tests for four of those mutations, and concluded that all the samples that matched came from a single batch, code-named RMR-1029, stored at Fort Detrick.

Ivins "has been the sole custodian of RMR-1029 since it was first grown in 1997," said one affidavit.

Powder from anthrax-laden letters sent to the New York Post and Tom Brokaw of NBC contained a bacterial contaminant not found in the anthrax-containing envelopes mailed to Leahy or Daschle, the affidavit said.

Investigators concluded that "the contaminant must have been introduced during the production of the Post and Brokaw spores," the affidavit said.

The documents disclosed that authorities searched Ivins' home on Nov. 2, 2007, taking 22 swabs of vacuum filters and radiators and seizing dozens of items. Among them were video cassettes, family photos, information about guns and a copy of "The Plague" by Albert Camus.