[3][4][5] At a news conference at the United States Department of Justice (DOJ) on August 6, 2008 (eight days after Ivins' suicide), FBI and DOJ officials formally announced that the Government had concluded that Ivins was likely solely responsible for the deaths of five people, and for the injury of dozens of others, resulting from the September–October 2001 mailings to members of Congress and to members of the media, of several anonymous letters which contained Bacillus anthracis, commonly referred to as anthrax.

[14] On May 15, 2011, the panel released its findings, which "conclude[d] that the bureau overstated the strength of genetic analysis linking the mailed anthrax to a supply kept by Bruce E.

"[11][15] The NAS committee stated that its primary finding was that "it is not possible to reach a definitive conclusion about the origins of the B. anthracis in the mailings based on the available scientific evidence alone.

When she discovered she was pregnant with Bruce, a pregnancy that was unplanned and unwanted, she repeatedly tried to abort the child by throwing herself down a set of stairs.

[22][23] His earliest known published work pertained to the response of peritoneal macrophages, a type of white blood cell, to infection by Chlamydia psittaci, an infectious bacterium that can be transmitted from animals to humans.

[26] In a 2006 paper published in the prestigious journal Proceedings of the National Academy of Sciences, he wrote with his co-authors Shortening the duration of antibiotic postexposure prophylaxis in a bioterrorism event involving B. anthracis by adding postexposure vaccination could greatly alleviate problems of noncompliance and side effects associated with prolonged antibiotic therapy.

The value of adding vaccination to postexposure antibiotic prophylaxis should be considered in planning the public health response to bioterrorism events involving inhalational anthrax.

[2] Starting in mid-October, he and his colleagues worked long hours testing samples to distinguish real anthrax letters from the numerous hoaxes that were sent out at this time.

[31] Ivins also helped the FBI analyze the powdery material recovered from one of the anthrax-tainted envelopes sent to a U.S. senator's office in Washington, D.C.[2] Results of the investigation were initially distributed to the public via ABC News, claiming "four well placed sources" had confirmed that "trace amounts of the chemical additives bentonite" were found in the anthrax samples, and that this was the chemical signature of Iraqi-made anthrax.

[28] In 2002, an investigation was carried out as a result of an incident at Fort Detrick where anthrax spores had escaped carefully guarded rooms into the building's unprotected areas.

[32] The incident called into question the ability of USAMRIID to keep its deadly agents within laboratory walls seven months after the anthrax mailings.

[36] When asked about the anthrax attacks and whether he could have had anything to do with them, the FBI said that Ivins admitted he suffered from loss of memory, stating that he would wake up dressed and wonder if he had gone out during the night.

"[40] The Los Angeles Times wrote that Ivins stood to profit from the attacks because he was a co-inventor on two patents for a genetically engineered anthrax vaccine.

"There are clearly a lot of unanswered questions," said Senator Chuck Grassley, who called for a congressional investigation into the allegations that Ivins was the anthrax killer.

Richard O. Spertzel, a microbiologist who led the United Nations' biological weapons inspections of Iraq, wrote that the anthrax used could not have come from the lab where Ivins worked.

"[54] The spores in the Daschle letter were 1.5 to 3 micrometres across, many times smaller than the finest known grade of anthrax produced by either the U.S. or Soviet bioweapons programs.

[54] An electron microscope, which costs hundreds of thousands of dollars, would be needed to verify that the target spore size had been consistently achieved.

[54] The presence of the anti-clumping additive silicon dioxide in the anthrax samples also suggests a high degree of sophistication as specialists working at Lawrence Livermore National Laboratory were unable to duplicate this property despite 56 attempts.

A psychiatrist engaged by The New York Times to analyze the released documents found evidence of psychoses, but could not rule out the possibility that Ivins was feigning or exaggerating mental illness for purposes of attention or sympathy.

[60][61][62] Social worker Jean C. Duley applied for a protective order, writing that Ivins had stalked and threatened to kill her and had a long history of homicidal threats.

"[65] According to an article originally appearing in the Frederick News-Post on August 12, 2009, Duley was under house arrest when she recorded Ivins' allegedly threatening messages.

[68] Ivins was subsequently committed for psychiatric evaluation and his home was raided by federal agents who confiscated ammunition and a bulletproof vest.

[14] Heine told the 16-member panel that producing the quantity of spores in the letters would have taken at least a year of intensive work using the equipment at the USAMRIID laboratory.

[14] On May 15, 2011, the panel released its findings, which "conclude[d] that the bureau overstated the strength of genetic analysis linking the mailed anthrax to a supply kept by Bruce E.

"[11] Following the release of an NAS report in February 2011, Congressman Rush D. Holt, Jr. (D-NJ), a physicist from whose district the anthrax letters were mailed, re-introduced legislation "to create a 9/11-style Commission, complete with subpoena power, with a mandate to review the entire matter.

[74] These were cited in the Department of Justice summary of the case against Ivins as suggesting that he may have harbored a grudge against pro-choice Catholic senators Daschle and Leahy, recipients of anthrax mailings.

[76] Dr. Nancy Haigwood, the director of the Oregon National Primate Research Center and a Kappa Kappa Gamma member who was a colleague of Ivins at the University of North Carolina when he was a post-doctoral fellow, later recounted to the New York Times a series of intrusive and unsettling interactions with Ivins in the late 1970s and 80s, claiming that "he damaged my property, he impersonated me and he stalked me".

[60] Such behavior does not appear to have been anomalous for Ivins, who himself admitted to FBI investigators that he once drove through the night to Ithaca, New York, to leave gifts for a young woman who had left her job in his laboratory to attend Cornell University.

[76] Authorities investigating the anthrax attacks found anthrax spores in a postal drop box located at 10 Nassau Street in Princeton, New Jersey, 300 feet (91 m) from a storage facility where the Princeton University chapter of Kappa Kappa Gamma kept rush paraphernalia, initiation robes, and other property as of 2001.

[80] The 2022 Netflix documentary, The Anthrax Attacks: In the Shadow of 9/11, features Bruce Ivins prominently and shows him portrayed by actor Clark Gregg in re-enactments.