FBI
Why was Atta forced to check two of his three bags?
September 11 attacks
Immediately after the attacks, the Federal Bureau of Investigation started PENTTBOM, the largest criminal inquiry in the history of the United States. At its height, more than half of the FBI's agents worked on the investigation and followed a half-million leads. The FBI concluded that there was "clear and irrefutable" evidence linking al-Qaeda and bin Laden to the attacks. The FBI was quickly able to identify the hijackers, including leader Mohamed Atta, when his luggage was discovered at Boston's Logan Airport. Atta had been forced to check two of his three bags due to space limitations on the 19-seat commuter flight he took to Boston. Due to a new policy instituted to prevent flight delays, the luggage failed to make it aboard American Airlines Flight 11 as planned. The luggage contained the hijackers' names, assignments and al-Qaeda connections. "It had all these Arab-language (sic) papers that amounted to the Rosetta stone of the investigation", said one FBI agent. Within hours of the attacks, the FBI released the names and in many cases the personal details of the suspected pilots and hijackers. By midday, the U.S. National Security Agency and German intelligence agencies had intercepted communications pointing to Osama bin Laden. On September 27, 2001, the FBI released photos of the 19 hijackers, along with information about possible nationalities and aliases. Fifteen of the men were from Saudi Arabia, two from the United Arab Emirates, one (Atta) from Egypt, and one from Lebanon.