9/11 Investigation (PENTTBOM)

Pentagon with American Flag draped over the west wall.

They were the most lethal terrorist attacks in history, taking the lives of 3,000 Americans and international citizens and ultimately leading to far-reaching changes in anti-terror approaches and operations in the U.S. and around the globe.

Our ensuing investigation of the attacks of 9/11/01—code-named “PENTTBOM”—was our largest investigation ever. At the peak of the case, more than half our agents worked to identify the hijackers and their sponsors and, with other agencies, to head off any possible future attacks. We followed more than half-a-million investigative leads, including several hundred thousand tips from the public. The attack and crash sites also represented the largest crime scenes in FBI history.

For more information:

Press Release of 9/27/2001 with photographs of the 19 hijackers
-- American Airlines #11
-- American Airlines #77
-- United Airlines #93
-- United Airlines #175
Zacarias Moussaoui: In April 2005, Moussaoui pled guilty to six charges against him related to his participation in the 9/11 conspiracy. In May 2006, he was sentenced to life in prison.
-- Director Mueller’s statement on the indictment on 12/11/2001
-- Indictment
FBI Agent Lenny Hatton—who died in the 9/11 attacks—is presented the heroes medal of valor. Former FBI Special Agent in Charge John P. O’Neill also lost his life in the attacks.

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