The FBI today said it has formally closed its investigation into the 2001 anthrax mailings that killed five people — including U.S. Postal Service workers Joseph Curseen and Thomas Morris — and sickened 17 others. The 96-page investigative summary posted here concludes that Army anthrax researcher Bruce Ivins, who committed suicide in 2008, acted alone:
Investigators learned that Dr. Ivins was alone late at night and on the weekend in the lab where RMR-1029 [the batch of anthrax spores used in the attacks]was stored in the days immediately preceding the dates on which the anthrax could have been mailed. Before the anthrax mailings, Dr. Ivins had never exhibited that pattern of working alone in the lab extensively during non-business hours, and he never did so after the anthrax attacks. When confronted, he was unable to give a legitimate explanation for keeping these unusual and, in the context of the investigation, suspicious hours.
[…] Dr. Ivins was among the very few anthrax researchers nationwide with the knowledge and ability to create the highly purified spores used in the mailings. Finally, everyone else who had access to RMR-1029 was ruled out as the mailer because, among other reasons, they lacked the ability and/or opportunity to prepare and store the material.
The report goes into more detail on Ivins’ obsessions and mental health problems and other suspicious activity before and after the anthrax mailings.