The investigators explained how they traced the anthrax used in the attacks back to Ivins' lab at Fort Detrick in Frederick, how Ivins allegedly stymied their investigation, and how what they called a history of mental illness and obsessive behavior helped them build a case that is circumstantial but, they said, irrefutable.
"The painstaking investigation led us to the conclusion that Dr. Bruce E. Ivins was responsible for the death, sickness and fear brought to our country by the 2001 anthrax mailings and it appears, based on the evidence, that he was acting alone," said Joseph Persichini, assistant director of the FBI's Washington field office.
Officials said they were taking the "extraordinary" step of releasing search warrants, affidavits and other documents because of keen public interest in the massive investigation into one of the most perplexing cases of domestic terrorism. But the disclosure also underscores the deep skepticism facing the FBI and the Justice Department, which were unable to solve the mystery for years.
Five people were killed and 17 injured from anthrax that was sent in letters to Congress and news organizations in September and October 2001. The lengthy federal probe into the attacks hit several dead-ends and led to a $5.8 million payment to a man wrongly identified as a person of interest, Steven J. Hatfill, who also worked at Fort Detrick.
A memorial service was held for Ivins yesterday at Fort Detrick, where the scientist had labored for decades to develop vaccines for anthrax. The service was attended by hundreds of soldiers, scientists and family members, according to Ivins' lawyers, who released a statement saying that no concrete evidence had been presented against their client.
"The government's press conference was an orchestrated dance of carefully worded statements, heaps of innuendo and a staggering lack of real evidence - all contorted to create the illusion of guilt by Dr. Ivins," said the lawyers, Paul F. Kemp and Thomas M. DeGonia. They have repeatedly said he was innocent.
But Ivins clearly knew investigators were closing in. His house had been under surveillance for a year, federal agents followed him wherever he went and he had been interviewed by investigators several times. Ivins had a history of mental illness, but the pressure led to a further decline in his condition, colleagues have said, to the point that he was hospitalized.
On July 9, Ivins was attending a group therapy session in Frederick. According to an affidavit released yesterday, he told the group he was a suspect in the anthrax investigation and that he was angry at the government and the investigators.
"He said he was not going to face the death penalty," the affidavit said, "but instead had a plan to kill co-workers and other individuals who had wronged him. He said he had a bulletproof vest, and a list of co-workers, and added that he was going to obtain a Glock firearm from his son within the next day, because federal agents are watching him and he could not obtain a weapon on his own."
He was admitted to a psychiatric wing of Frederick Memorial Hospital the next day. Shortly after he was released, on July 24, he took the overdose of Tylenol and codeine that killed him.
Yesterday, federal lawyers asked a judge in Washington to unseal search warrants and affidavits that spelled out their case, and FBI Director Robert S. Mueller III met with families of the anthrax victims and lawmakers to lay out the evidence against Ivins. One congressman who was briefed said that the presentation was "compelling" but that he was not convinced Ivins acted alone.
According to documents released, investigators traced the anthrax to Ivins' lab in 2005 using newly developed genetic mapping techniques. They concluded that all the anthrax used in the mailings that led to fatalities came from a single flask of anthrax spores known as RMR-1029.
That flask was "created and solely maintained by Dr. Ivins," said Jeffrey Taylor, U.S. attorney for the District of Columbia. "No one received material from that flask without going through Dr. Ivins. We thoroughly investigated every other person who could have had access to the flask, and we were able to rule out all but Dr. Ivins."
The time needed for that investigation explains why Ivins was not identified as the principal suspect until two years later, in 2007, Taylor said. There was "a tremendous amount of additional investigation that needs to take place to identify the universe of individuals who have access to that flask," he said. "We're talking about a large number of individuals, over 100, who potentially had access to this substance."
Ivins' off-hours time in the lab also raised suspicions. Just before the first set of anthrax letters was mailed, on Sept. 18, 2001, Ivins spent long hours at night in the lab containing the anthrax. And then again, before the second set of letters was mailed, on Oct. 9, he spent many night hours in the lab. He was alone during that time, officials said, suggesting he had the time to convert the anthrax into the deadly form that turned up in the letters.
When investigators asked Ivins about those extended hours, he offered "no legitimate reason," according to an affidavit, except that "home was not good" and he went to the lab "to escape."
Ivins "engaged in behavior and made a number of statements that suggest consciousness of guilt," Taylor said, including discarding a book on DNA coding while under round-the-clock surveillance. And in 2002, when investigators asked Ivins to provide a set of anthrax samples from the RMR-1029 flask, he provided a different set instead.
The correct sample was not provided until 2004.
Investigators also released e-mails yesterday that they said point to Ivins' guilt. On Sept. 26, 2001, Ivins wrote, "Bin Laden terrorists for sure have anthrax ... Osama Bin Laden has just decreed death to all Jews and all Americans." One of the anthrax mailings included the statement: "WE HAVE THIS ANTHRAX ... DEATH TO AMERICA ... DEATH TO ISRAEL."
The e-mails also chronicle Ivins' mental condition. Around the time of the attacks, he wrote a number of e-mails in which he seeks to understand his mental health issues. At one point, he writes that his psychiatrist and counselor believe he has a "Paranoid Personality Disorder" and he says that he has "incredible paranoid, delusional thoughts at times."
Ivins was also troubled during that time because an anthrax vaccine project on which he was working was failing, and he believed that success of the venture was important, the federal authorities said.
"One theory is that by launching these attacks, he creates a situation, a scenario where people realize they need to have this vaccine," Taylor said yesterday.
Officials also sought to explain why the anthrax letters - sent to the offices of Sens. Patrick J. Leahy and Tom Daschle as well as NBC News, The Washington Post and the Sun tabloid in Florida - were all mailed from Princeton, N.J. Ivins had a habit of traveling long distances to mail letters to disguise the sender, officials said.
They also said he was obsessed with the Kappa Kappa Gamma sorority, and the street box in Princeton from which the letters were posted is just 60 feet from a Kappa Kappa Gamma office. Among other evidence presented in the affidavits, one of the documents quotes a posting on a Web site last year in which Ivins wrote that the sorority had "labeled me as an enemy decades ago, and I can only abide by their 'Fatwah' on me."
Furthermore, investigators determined that the pre-stamped envelopes used in the mailings were bought from a Frederick post office where Ivins had a box. He was also a prolific writer to Congress and the media. A search of his house last fall turned up 68 such letters.
Officials acknowledged lacking direct evidence to connect Ivins to the anthrax attacks but said the circumstantial evidence was overwhelming.
"We have a flask that's effectively the murder weapon from which those spores were taken that was controlled by Dr. Ivins," Taylor said. "The anthrax in that flask was created by Dr. Ivins. We have the suspicious behavior that he had undertaken over the years.
"Circumstantial evidence, sure. Some of it is," Taylor continued. "But it's compelling evidence and in our view would have helped us prove the case against Dr. Ivins beyond a reasonable doubt."
Daschle said yesterday that he would not comment until he had a chance to review the evidence released. Rep. Rush Holt, whose central New Jersey district includes Princeton, said the evidence was "compelling" after receiving a briefing from the FBI director.
But, Holt said, "a number of important questions remain unanswered, such as why investigators remained focused on Dr. Hatfill long after they had begun to suspect Dr. Ivins of the crime and why investigators are so certain that Ivins acted alone."