WASHINGTON  After four years pursuing one former Army scientist on a costly false trail, F.B.I. agents investigating the deadly anthrax letters of 2001 finally zeroed in last year on a different suspect: another Army scientist from the same biodefense research center at Fort Detrick in Frederick, Md.
Over the last 18 months, even as the government battled a lawsuit filed by the first scientist, Steven J. Hatfill, investigators built a case against the second one, Bruce E. Ivins, a highly respected microbiologist who had worked for many years to design a better anthrax vaccine.
Last weekend, after learning that federal prosecutors were preparing to indict him on murder charges, Dr. Ivins, a 62-year-old father of two, took an overdose of Tylenol with codeine. He died in a Frederick hospital on Tuesday, leaving behind a grieving family and uncertainty about whether the anthrax mystery had finally been solved.
The apparent suicide of Dr. Ivins, a Red Cross volunteer and amateur juggler who had won the Defense Department’s highest civilian award in 2003, was a dramatic turn in one of the largest criminal investigations in the nation’s history. The attack, the only major act of bioterrorism on American soil, came in the jittery aftermath of the Sept. 11 attacks. It killed five people, sickened 17 others and set off a wave of panic.
NBC anthrax letter sent to Tom Brokaw.A man about to be indicted by the United States Department of Justice died Tuesday. His lawyer has called the death a suicide.

Bruce Edwards Ivins, 62, was taken to Frederick Memorial Hospital in Frederick, Maryland, where he died of an overdose of Tylenol and codeine, the ''Los Angeles Times'' reported Friday.

Ivins, who worked at the biodefense laboratories in Fort Detrick, Maryland for 18 years, was about to be charged by the Justice Department in connection with the 2001 anthrax attacks, which killed five people and infected 17 others.

Ivin's lawyer, Paul Kemp, insisted that his client had no role in the attacks, which targeted politicians in Washington DC, and members of the media in New York City and Florida.

"For six years, Dr. Ivins fully cooperated with that investigation, assisting the government in every way that was asked of him," Mr. Kemp told the ''New York Times''. "The relentless pressure of accusation and innuendo takes its toll in different ways on different people, as has already been seen in this investigation. In Dr. Ivins’ case, it led to his untimely death."

Both the ''New York Times'' and the ''Los Angeles Times'' report that Ivins assisted the FBI and other agencies in the investigation after the 2001 attacks.

The ''Los Angeles Times'' reports that Ivins was reinvestigated beginning in 2006 after FBI Director Robert Mueller changed the case's leadership. Before then, the only labeled "person of interest" was Steven J. Hatfill. He has since been cleared and paid between $4.6 and $5.82 million by the U.S. Government as part of a settlement stemming for 2003 law suits filed against the Justice Department and government officials, including former Attorney General John Ashcroft.

The ''New York Times'' also reported that a spokesman for Hatfill said that rushing to judgment in the case is a mistake.

“Everybody is jumping to the conclusion that because this guy committed suicide, he must be the anthrax killer,” Mr. Clawson told the ''New York Times''. “That is a lousy premise. The pressure of these F.B.I. investigations on individuals is phenomenal, and it is quite likely that this guy cracked under that pressure but had nothing to do with the killings.”

The ''New York Times'' reports that Ivins had been undergoing psychiatric treatment within the last month and had a restraining order placed on him by a woman he was allegedly stalking and threatening.

According to National Public Radio (NPR), mental health professional Jean C. Duley requested that Frederick County court issue a "peace order", a type of restraining order, against Ivins in July. Duley submitted documents to the court which show a history of "homicidal actions, threats and plans."

The ''New York Times'' also reports that Ivins was a religious man. Members of his congregation gathered early Friday to pray for him at St. John the Evangelist Roman Catholic Church in Frederick.

The Associated Press cites one of Ivins' colleagues who said he had been removed from his work area as he was thought to be a potential threat to others. According to NPR, one colleague said he was "emotionally fractured by the federal scrutiny."