Anthrax Wall

The 2001 anthrax attacks, also known as Amerithrax (a portmanteau of "America" and "anthrax", from its FBI case name), occurred in the United States over the course of several weeks beginning on September 18, 2001, one week after the September 11 attacks. Letters containing anthrax spores were mailed to several news media offices and to senators Tom Daschle and Patrick Leahy, killing five people and infecting seventeen others. Capitol police officers and staffers working for Senator Russ Feingold were exposed as well. According to the FBI, the ensuing investigation became "one of the largest and most complex in the history of law enforcement". They are the only lethal attacks to have used anthrax outside of warfare.

The FBI and CDC authorized Iowa State University to destroy its anthrax archives in October 2001, which hampered the investigation. In the following weeks, US officials and media unsuccessfully attempted to link the attacks to Al-Qaeda and/or Ba'athist Iraq. Thereafter, a major focus in the early years of the investigation was bioweapons expert Steven Hatfill, who was eventually exonerated. Bruce Edwards Ivins, a scientist at the government's biodefense labs at Fort Detrick in Frederick, Maryland, became a focus around April 4, 2005. On April 11, 2007, Ivins was put under periodic surveillance and an FBI document stated that he was "an extremely sensitive suspect in the 2001 anthrax attacks". On July 29, 2008, Ivins died by suicide with an overdose of acetaminophen (paracetamol).

Federal prosecutors declared Ivins the sole perpetrator on August 6, 2008, based on DNA evidence leading to an anthrax vial in his lab. Two days later, Senator Chuck Grassley and Representative Rush D. Holt Jr. called for hearings into the Department of Justice and FBI's handling of the investigation. The FBI formally closed its investigation on February 19, 2010.

In 2008, the FBI requested a review of the scientific methods used in their investigation from the National Academy of Sciences, which released their findings in the 2011 report Review of the Scientific Approaches Used During the FBI's Investigation of the 2001 Anthrax Letters. The report cast doubt on the government's conclusion that Ivins was the perpetrator, finding that the type of anthrax used in the letters was correctly identified as the Ames strain of the bacterium, but that there was insufficient scientific evidence for the FBI's assertion that it originated from Ivins' laboratory.

The FBI responded by saying that the review panel asserted that it would not be possible to reach a definite conclusion based on science alone, and said that a combination of factors led the FBI to conclude that Ivins had been the perpetrator. Some information is still sealed concerning the case and Ivins' mental health. The government settled lawsuits that were filed by the widow of the first anthrax victim Robert Stevens for $2.5 million with no admission of liability. The settlement was reached solely for the purpose of "avoiding the expenses and risks of further litigations", according to a statement in the agreement.