Aug. 1 (Bloomberg) -- A government scientist facing the prospect of being charged with killing five people in the 2001 anthrax attacks died this week in an apparent suicide, government officials said.

Bruce E. Ivins, 62, died July 29 at Frederick Memorial Hospital in Frederick, Maryland. Federal prosecutors were planning to seek the death penalty against him, one official said.

Ivins worked at the U.S. biodefense laboratory at Fort Detrick, Maryland, and helped federal investigators analyze anthrax samples used in the attacks. Today, Ivins's attorney issued a statement saying the scientist was innocent and had fully cooperated with the FBI's investigation for six years.

``We assert his innocence in these killings, and would have established that at trial,'' said Paul Kemp, a partner at the Venable law firm in Rockville, Maryland. ``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's case, it led to his untimely death.''

The deaths from anthrax spores anonymously mailed to news organizations and members of Congress shook the U.S. seven years ago as the nation was still reeling from the Sept. 11 terrorist attacks. Postal facilities and some U.S. Senate offices were closed during the initial investigation. Television news anchors Tom Brokaw and Dan Rather were targeted along with U.S. Senators Tom Daschle and Patrick Leahy.

No Autopsy

Ivins's death is being investigated as an apparent suicide from a drug overdose, said Lieutenant Shawn Martyak of the Frederick Police Department's criminal investigation division. Based on laboratory test results of blood taken from the body, the state medical examiner ``determined that an autopsy wouldn't be necessary'' to determine the cause of death, Martyak said.

The Los Angeles Times, which first reported the story, said Ivins took an overdose of prescription Tylenol with codeine.

The Federal Bureau of Investigation has come under fire for failing to solve the crimes. In June, the U.S. agreed to pay a settlement valued at $5.8 million to resolve a lawsuit by another Fort Detrick researcher, Steven Hatfill, who said the government improperly identified him publicly as a ``person of interest'' in the case.

Representative Rush Holt, a Democrat whose central New Jersey district is believed to have housed the postal box where the anthrax-laced letters were mailed, today asked FBI Director Robert Mueller in a letter to say whether Ivins's death means the investigation is over.

`Poorly Handled'

``The public, the victims' families and law enforcement would like to know that the book is closed on this investigation,'' Holt said in a statement. ``What we learn will not change the fact that this has been a poorly handled investigation that has lasted six years and already has resulted in a trail of embarrassment and personal tragedy.''

In a statement, the Justice Department said, ``We are able to confirm that substantial progress has been made in the investigation by bringing to bear new and sophisticated scientific tools.''

The agency said it wouldn't provide more details because investigative documents are under court seal, and officials need to speak with families of the victims of the attacks.

``We anticipate being able to provide additional details in the near future,'' the statement said.

Committed to Hospital

According to Maryland state court documents, Ivins had recently been committed temporarily to a mental hospital outside Baltimore, and a judge ordered him to stay away from a woman who accused him of threatening to kill her.

Jean Duley, identified by the Frederick News-Post as a mental-health counselor, filed a handwritten petition to the court saying Ivins ``has a history dating to his graduate days of homicidal threats'' and that his psychiatrist ``called him homicidal, sociopathic.''

Duley also said she had been subpoenaed to testify before a federal grand jury in Washington on Aug. 1. Her petition to the court said ``FBI involved'' and added that Ivins ``will be charged w/5 capital murders.''

An attorney for Duley declined to comment. Duley was identified in a June 29 article in the Frederick newspaper as a program director for Comprehensive Counseling Associates, a local mental-health counseling center. A woman who answered the phone at the center said Duley no longer worked there.

`Mourns the Loss'

Caree Vander Linden, a spokeswoman for the U.S. Army Medical Research Institute of Infectious Diseases at Fort Detrick, said the agency ``mourns the loss of Dr. Bruce Ivins, who served the institute for more than 35 years as a civilian microbiologist.''

Ivins's death was announced yesterday in an obituary in the News-Post. The newspaper's online edition also carried a compilation of letters to the editor written by Ivins.

Ivins, whose identity as a suspect hadn't been disclosed publicly, became depressed after the Hatfill settlement was announced and told a therapist he was considering suicide, the Los Angeles Times said, citing an unidentified colleague.

The newspaper said that Ivins had earlier come under scrutiny from Army officials because he failed for five months to report anthrax contaminations in the lab. He told investigators that it was a mistake not to have reported the incidents, which occurred from December 2001 to April 2002.

The Army chose not to discipline Ivins because it didn't want to discourage employees from reporting such spills, the Times said.

In a telephone interview, Ivins's brother Tom said that 18 months ago he spoke with an FBI agent and postal inspector ``who talked to me about family situations.''

Bruce Ivins was married to Diane Ivins for 33 years, and they had a son and a daughter, according to the News-Post obituary. A memorial service was scheduled for Aug. 9 in Frederick.

To contact the reporters on this story: Robert Schmidt in Washington at rschmidt5@bloomberg.net; James Rowley at jarowley@bloomberg.net

Last Updated: August 1, 2008 17:36 EDT