"Bruce E. Ivins had worked for 18 years at the government's bio defense labs at Fort Detrick and was a top biodefense researcher. The Associated Press reported on August 1, 2008 that he had apparently committed suicide at the age of 62. It was widely reported that the FBI was about to press charges against him, but the evidence was largely circumstantial and the grand jury in Washington reported that it was not ready to issue an indictment. Rush D. Holt, Jr. represented the district where the anthrax letters were mailed, and he said that circumstantial evidence was not enough and asked FBI director Robert S. Mueller to appear before Congress to provide an account of the investigation. Ivins' death left two unanswered questions. Scientists familiar with germ warfare said that there was no evidence that he had the skills to turn anthrax into an inhalable powder. Alan Zelicoff aided the FBI investigation, and he stated: "I don't think a vaccine specialist could do it…. This is aerosol physics, not biology".
W. Russell Byrne worked in the bacteriology division of the Fort Detrick research facility. He said that Ivins was "hounded" by FBI agents who raided his home twice, and he was hospitalized for depression during that time. According to Byrne and local police, Ivins was removed from his workplace out of fears that he might harm himself or others. "I think he was just psychologically exhausted by the whole process," Byrne said. "There are people who you just know are ticking bombs. He was not one of them."
On August 6, 2008, federal prosecutors declared Ivins to be the sole perpetrator of the crime when US Attorney Jeffrey A. Taylor laid out the case to the public. "The genetically unique parent material of the anthrax spores… was created and solely maintained by Dr. Ivins."
According to the report on the Amerithrax investigation published by the Department of Justice, Ivins engaged in actions and made statements that indicated a consciousness of guilt. He took environmental samples in his laboratory without authorization and decontaminated areas in which he had worked without reporting his activities. He also threw away a book about secret codes, which described methods similar to those used in the anthrax letters. Ivins threatened other scientists, made equivocal statements about his possible involvement in a conversation with an acquaintance, and put together outlandish theories in an effort to shift the blame for the anthrax mailings to people close to him.:9
The FBI said that Ivins's justifications for his actions after the environmental sampling, as well as his explanations for a subsequent sampling, contradicted his explanation for the motives for the sampling.
According to the Department of Justice, flask RMR-1029, which was created and controlled by Ivins, was used to create "the murder weapon"
 Doubts about anthrax story The Baltimore Sun August 5, 2008
 "Scientist's Suicide Linked to Anthrax Inquiry" The New York Times August 2, 2008
 US officials release evidence against anthrax scientist Bruce Ivins".
Dishneau, David (August 2, 2008). "Ivins had mild persona, but some saw dark side".
USA Today. Associated Press. Retrieved October 10, 2011.
US officials release evidence against anthrax scientist Bruce Ivins(3 results)
U.S FBI formally closes 2001 anthrax mailings case, concludes researcher Dr. Bruce Ivins acted alone
By THE ASSOCIATED PRESS
US officials release evidence against anthrax scientist Bruce Ivins
By JAMES GORDON MEEK, GREG B. SMITH, DAVID SALTONSTALL
Justice Department likely to shut down FBI anthrax investigation
By JAMES GORDON MEEK, DAVID SALTONSTALL
 FBI file #847376 pp. 6, 11