News reports say that federal authorities are confident that a top research scientist charged with creating new defenses against biological agents is responsible for the 2001 mailings of letters containing anthrax spores that kiled 5 people and wounded 17 more. However, in the wake of that scientist's apparent July 29 suicide, friends, colleagues and independent observers are skeptical.

The scientist, Bruce Ivins, 62, had been a microbiologist at a major government-run biodefense research center since 1980. Ivins worked on anthrax vaccines, and reportedly stood to profit from some of the treatments he helped to invent.

Federal investigators had been regularly questioning Ivins and other researchers who had access to anthrax spores ever since 2001. However, prosecutors and Ivins' lawyer told journalists that Ivins had recently been informed that the government would soon be seeking a murder indictment against him. Since the case is still officially active, the FBI's only public statement is an August 1 announcement that "substantial progress has been made by bringing to bear new and sophisticated scientific tools."

Speculation about Ivins' psychological state and possible motives gained steam when the New York Times posted a recording of a July 24 court hearing at which social worker Jean Duley sought a restraining order against Ivins on the grounds that he admitted to having tried to kill people for the past eight years. (You can hear the recording here.) Duley also said that Ivins had been labeled sociopathic and homicidal by "several top psychiatrists."

According to Bloomberg News, court documents said that Ivins had recently been temporarily committed to a psychiatric facility in Maryland. (hat tip to JReid.)

But scientists who worked with Ivins aren't buying, partially because the stories don't fit the man they knew, and also because they are mindful of the government's failed pursuit of another scientist, Steven Hatfill. In June, 2008, Hatfill, 54, won a $5.62 milion settlement against the Justice Department and FBI for invading his privacy and ruining his career.

One person who says she is sure Ivins isn't the anthrax killer is Maine physician and blogger, Meryl Nass MD. Nass, who has testified before Congress on her work with patients sickened by Gulf War Syndrome and exposure to experimental anthrax vaccines, says the reported case against Ivins doesn't fit the colleague she knew and interacted with over the last two decades.

I first met Bruce at a conference on biowarfare in the spring of 1991
at the University of Maryland. We happened to sit next to each other,
in the front row, and enjoyed chatting. Bruce sent me information
relevant to my research on Zimbabwe's anthrax epidemic, and I commented
on his work. We continued to correspond occasionally for about ten
years. Bruce had a chronic blood disorder, which he thought might have
been due to his many anthrax immunizations, and encouraged me to
continue investigating the vaccine's side effects. He shared papers
with me on the effects of the vaccine's aluminum adjuvant in
experimental animals.

Now it turns out that Bruce was one of
several scientists the justice department turned its spotlight on,
after Hatfill succeeded in not only getting them to leave him alone,
but also pay him for destroying his (admittedly tawdry) reputation.
Bruce was a gentle guy, the opposite of Hatfill. While Hatfill stirred
up a cauldron of controversy, held press conferences and initiated many
legal efforts (I was subpoenaed as a witness for his case against the
New York Times), Bruce got depressed. Then killed himself, apparently.

Nass agrees with scientists interviewed by the Washington Post that Ivins didn't have the "motive nor the means" to get the specific kind of powder used in the mailings. Prosecutors reportedly say that Ivins did have the means. Further the AP is reporting that a new DNA analysis tool confirmed that the strain of anthrax found in the letters came from Ivins' lab. (Note to AP boycotters: I couldn't find the story anywhere else.)

Nass also wonders about Jean Duley's credibility and motives -- did Duley report Ivins' threats to the proper authorities? Why is she reportedly in hiding now?

Meanwhile, blogger and law professor Ann Althouse jumps completely into the deep end of the speculation pool by asking why Ivins would commit suicide if he was innocent? According to news reports, there won't be an autopsy on Ivins' body, so some questions about his death may never be answered.

TChris at TalkLeft argues that the only way to resolve all of the questions is for the FBI to release its files on Ivins:

The FBI views the
suicide as a confession. In the absence of a suicide note that actually
admits the crime, that assertion is speculative. Ivins' lawyer points
out that people who are dogged with life-ruining accusations, true or
false, might lose the will to live.

Of course, Nass is not a mental health professional. And it is possible for sociociopaths to be utterly charming. However,
there is a valid question here: if Duley is correct that psychiatrists
had determined that Ivins was a murderous sociopath, what was done
about him? Did he retain his job and security clearance after receiving
such a dangerous diagnosis?

According to NPR, the FBI might offer a public briefing next week, after seeking a declaration that the case is officially closed and sharing information with the families of the victims of the attacks. However it's likely that questions and controversy will linger, no matter what the FBI does.