One of the nation's top biodefense researchers has apparently taken his own life, just as the FBI zeroed in on him as a suspect in the deadly 2001 anthrax attacks.
Sources familiar with the investigation tell ABC News that 62-year-old Bruce E. Ivins, who worked at the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID) at Fort Detrick, Md., died at a Maryland hospital Tuesday of a prescription drug overdose. The story of the Ivins investigation was first reported by the Los Angeles Times.
A source familiar with the investigation told ABC News that the government did not officially notify Ivins that he was a target of the investigation or that he was close to being indicted.
Ivins' attorneys learned of the government's intent to move forward with the prosecution of their client after he died on Tuesday, but had suspected the case was headed in that direction based on investigators' focus on the scientist, the source said.
Ivins' death came as FBI agents had been aggressively interviewing friends, family and associates about the possibility he was responsible for a series of anthrax mailings in the fall of 2001 that left five dead, sickened 17 and terrorized a nation still reeling from the Sept. 11 attacks.
The Justice Department released a statement on the anthrax investigation Friday, noting that there have been "significant developments" in the joint DOJ, FBI and U.S. Postal Inspection Service probe, but declining to go into detail.
Though they were "able to confirm that substantial progress has been made in the investigation by bringing to bear new and sophisticated scientific tools," the statement added that the investigative agencies "have significant obligations to the victims of these attacks and their families that must be fulfilled before any additional information on the investigation can be made public."
Additionally, investigative documents in the case remain under seal, but the statement said investigators "anticipate being able to provide additional details in the near future."
"I think it's incredibly disheartening that we as victims and survivors will never be able to sit in a courtroom with this man -- if indeed he was the person responsible -- and face him, and share with him how he so dramatically traumatized us and forever changed our lives," victim Casey Chamberlain, a former executive assistant at NBC News, said in a statement.
"I will never stop thinking about this case as long as I live."
Ivins had actually helped the FBI in the anthrax investigation and had ties to the location in New Jersey where the anthrax was mailed. The toxin arrived via mail to Capitol Hill offices and at news organizations in Florida and New York.
In a statement released Friday morning, Ivins' attorneys, led by Paul F. Kemp, asserted his late client's innocence and said they are "disappointed that we will not have the opportunity to defend his good name and reputation in a court of law."
Ivins had cooperated with investigators and appeared before the grand jury "many times," but had consistently maintained his innocence, the source familiar with the investigation told ABC News. His defense team had noticed Ivins was under increasing strain as a result of the investigation, and there was concern about how he was handling the news, the source said.