The scientist was the sole custodian of anthrax spores genetically identical to the powder used in 2001 attacks, say documents unsealed Wednesday.
RMR-1029 has been stored in the B3 biocontainment suite of Building 1425 of Fort Detrick, Md., ever since it was cultivated over a decade ago.
Dr. Ivins had unrestricted access to that suite – and was RMR-1029's sole custodian.
All of the powdered poison used in the anthrax attacks that shook the country in 2001 had four genetic mutations found only in RMR-1029, according to court documents unsealed Wednesday.
And around the time of the attacks, Dr. Ivins spent an unusual number of late nights in the lab for which FBI agents claimed he had no good explanation.
"His access to Suite B3 ... afforded all of the equipment and containment facilities which would have been needed to prepare the anthrax and letters used in the Fall 2001 attacks," according to one affidavit.
Ivins committed suicide last week as the Department of Justice readied charges against him. The microbiologist, who had worked on developing an anthrax vaccine, was respected by fellow scientists and received a top Defense Department award in 2003 for his research at Fort Detrick's US Army Medical Institute of Infectious Diseases.
Some of his neighbors and co-workers had criticized the heavy-handed tactics used against him by investigators and maintained that Ivins was a fragile person who cracked under the strain of being a suspect.