The FBI's new top investigators - Vincent B. Lisi and Edward W. Montooth - instructed agents to re-examine leads or potential suspects that might have received insufficient attention.
Moreover, significant progress was made in analyzing properties of the anthrax powder recovered from separate letters that were addressed to two U.S. senators.
The renewed efforts led the FBI back to USAMRIID, where agents had first questioned scientists in December 2001, a few weeks after the fatal mailings.
By spring of this year, FBI agents were still contacting present and former colleagues of Ivins. At USAMRIID and elsewhere, scientists acquainted with Ivins were asked to sign confidentiality agreements to prevent leaks of new investigative details.
Soon after the government's settlement with Hatfill was announced June 27, Ivins began showing signs of serious strain. One of his longtime colleagues told the Times that Ivins, who was being treated for depression, indicated to a therapist that he was considering suicide.
Soon thereafter, family members and local police officers escorted Ivins away from USAMRIID, where his access to sensitive areas was curtailed, the colleague said.
Ivins was committed to a facility in Frederick for treatment of his depression.
On July 24, he was released from the facility, operated by Sheppard Pratt Health System. A phone call that same day by the Times verified that Ivins's government voice mail was still functioning.
The scientist faced forced retirement, planned for September, said his longtime colleague, who described Ivins as emotionally fractured by the federal scrutiny.
"He didn't have any more money to spend on legal fees. He was much more emotionally labile, in terms of sensitivity to things, than most scientists. ... He was very thin-skinned."
A spokeswoman for the FBI, Debra Weierman, said yesterday that the bureau would not comment regarding the death of Ivins. Last week, however, the FBI director told CNN that, "in some sense, there have been breakthroughs" in the case.
"I'll tell you we made great progress in the investigation," Mueller said. "And it's in no way dormant."
Ivins, the son of a Princeton-educated pharmacist, was born and raised in Lebanon, Ohio, and received undergraduate and graduate degrees, including a Ph.D. in microbiology, from the University of Cincinnati.
The elder of his two brothers, Thomas Ivins, said he was not surprised by the events that have unfolded.
"He buckled under the pressure from the federal government," Thomas Ivins said, adding that FBI agents came to Ohio last year to question him about his brother.
"I was questioned by the feds, and I sung like a canary," Thomas Ivins said, referring to his efforts to describe his brother's personality and tendencies.
"He had in his mind that he was omnipotent."
Ivins' widow declined to be interviewed when reached yesterday at her home in Frederick.The couple raised twins, who are now 24 years old.
David Willman writes for the Los Angeles Times.
