Dr. Russell Byrne, a former colleague of scientist Bruce E. Ivins, the government expert who killed himself as he was about to be charged by the Justice Department with conducting the 2001 anthrax attacks, alleges that the pressure of the investigation drove his former co-worker to take his own life.

Monday on the TODAY show, Dr. Russell Byrne depicted the slow decline of Ivins' mood as pressure against him increased from the FBI. The thing that apparently made him go over the top was the moment when he was removed from the Fort Detrick laboratories by police after ranting about weapons and making death threats, and admitted to a psychiatric ward.

Byrne is not the only one who challenges the accusations against Ivins. Former colleague David R. Franz told AP that it is highly unlikely, very improbable, that Bruce Ivins could have manufactured the anthrax powder at the government facility without being noticed. This is also an issue which Dr. Byrne has underlined on TODAY.

While Ivins' therapist, Jean C. Duley, said he was a "sociopathic, homicidal killer" who was thinking about murdering his colleagues, it doesn't actually prove that he was behind the anthrax attacks of 2001. Even if the psychologist's assessment is correct, it might be an accurate description of a man drove over the edge by the accusations which ruined his successful career as a biowarfare expert.

Colleagues testified that they did not notice anything amiss in Bruce Ivins' behavior before his mental health began deteriorating following the recent investigation. He would apparently weep at his desk, and was unable to do his work. Byrne also called the alleged motive to carry out the 2001 attacks bogus.

Ivins died Tuesday at Frederick Memorial Hospital after taking a massive dose of prescription Tylenol mixed with codeine. He helped the FBI investigate an anthrax-tainted envelope sent to a US senator’s Washington office, as a microbiologist for a government laboratory. For the past 18 years, Irvin worked at the government’s elite biodefense research laboratories at Fort Detrick, Md. He had played a central role in research to improve anthrax vaccine by preparing anthrax formulations used in experiments on animals, and was decorated for his outstanding contribution to biodefense.

Did the pressure by the government's investigation drive Ivins to kill himself? We might never know. Was he guilty of the 2001 attacks, and the anthrax indeed could be traced to him? If the anthrax tracing is as accurate as the recent Salmonella tracking by our government, or much like the botched Hatfill case, we might also never know that either. Former Sen. Tom Daschle, who was Senate majority leader at the time of the 2001 anthrax attacks, said he was also very skeptical of the investigation.