I find the FBI's case against Ivins persuasive, if not conclusive. Assuming most of the content of their Amerithrax Investigative Summary (PDF) is accurate, it seems probably that Ivins did commit the murders. If this stuff is true, he really was a mad scientist. I recently spent a considerable amount of time dealing with a person suffering from schizophrenia. What the FBI is describing is really quite similar to what my friend was going through. Especially the fixation on women who had rejected him in the past, his continuing irrational sense of connection to them, and a frequently expressed desire for revenge.

The time he spent in the hot room prior to each mailing, his demonstrated proclivity to travel to remote locations and mail packages anonymously, his evasive and irrational response to the investigation, his record of serious mental health problems, his access to the murder weapon and sill in manipulating it all suggest his guilt.

Now here is an interesting fact about one of the most vocal critics of the FBI's conclusion. According the the FBI's own report, Meryl Nass was a nemesis of Ivins's.

2. Dr. Ivins was being subjected to increasing public criticism for his work.

Compounding the intense professional pressure on Dr. Ivins was the increasingly vocal chorus of critics against him. Chief among these were journalist Gary Matsumoto, scientist Meryl Nass, and lawyer Mark S. Zaid, who blamed the anthrax vaccine for causing Gulf War Syndrome – ailments suffered by veterans of the first Gulf War in the early 1990s. Through the end of the summer and into the fall of 2001, Dr. Ivins was expressing his increasing frustration with this criticism of the work he had been doing. This frustration was only compounded by demands for more information regarding the anthrax vaccine research program, largely from Matsumoto, who had written a critical article in Vanity Fair magazine in May 1999, and who was working on a follow-up book entitled Vaccine A (which was eventually published in 2004). Within days of reading Matsumoto’s Vanity Fair article, Dr. Ivins commented in an e-mail to a former colleague: “[T]hanks for passing these along to me. I wonder when the National Enquirer will come out with its headlines on ‘Guinea Pig Soldiers Get Killer Vaccine.’”

Dr. Ivins’s offense at these criticisms grew as Matsumoto was making FOIA requests for information regarding the vaccine program for use in the critical Vaccine A. For example, just before the letter attacks, in August and September 2001, Dr. Ivins sent e-mails to a co-worker and a supervisor, a sample of which included, “Tell Matsumoto to kiss my ass. We’ve got better things to do than shine his shoes and pee on command. He’s gotten everything from me he will get.” The prosecution team learned more about the depth of Dr. Ivins’s animosity towards Matsumoto in a February 13, 2008 interview, in which Dr. Ivins stated that had actually gone to a Matsumoto website in recent years under the anonymous name “Guest,” and made sarcastic, provocative postings – one of many examples of Dr. Ivins’s ability to harbor grudges and, in his
own words, “stir the pot.”

Similarly, over the years, Dr. Ivins continued to speak disparagingly of Meryl Nass, another prominent critic, in much the same vein. Those who worked for him knew that Nass was one of those topics to avoid discussing around Dr. Ivins. They also noted that Dr. Ivins took criticism, especially of his work, very personally.
Finally, lawyer Mark S. Zaid filed the greatest number of FOIA requests related to the anthrax vaccine. Zaid, Executive Director of The James Madison Project,27 represented military clients who were refusing to take the anthrax vaccine. Zaid began sending e-mails to Dr. Ivins and others at USAMRIID as far back as 1999 requesting information regarding the vaccine. In addition, during the November 1, 2007 search of the Ivins residence, recovered from a black briefcase which Dr. Ivins had labeled “Attorney-Client Privilege” (but was ultimately determined by a filter team not to contain privileged material) was a laminated July 18, 2000 Washington Post article entitled “Anthrax Shots’ Effect Challenged (Army Disputes Expert Who Reviewed Vaccine Tests).” The article discussed a report by Dr. Ivins, dated September 23, 1991, in which he noted that “[a]lthough all vaccinated monkeys (C1-C10) survived, they appeared to be sick over the course of two weeks post-challenge.” The Washington Post article drew the conclusion that vaccinated soldiers would have the same symptoms: “Soldiers who are exposed to anthrax may become quite sick and be incapacitated for up to two weeks, even if they have received the full set” of anthrax vaccinations.