Final Report of the William H. Webster Commission on the Federal Bureau of Investigation, Counterterrorism Intelligence, and the Events at Fort Hood, Texas on November 5, 2009 [open pdf - 6MB]
"On December 17, 2008, United States Army Major Nidal Malik Hasan visited the website of radical Islamic cleric Anwar al-Aulaqi. He sent a message to Aulaqi. The Federal Bureau of Investigation acquired the message. A second message followed on January 1, 2009. Members of the Joint Terrorism Task Force (JTTF) in the San Diego Field Office reviewed the messages. Concerned by the message's content and implications that the sender was a U.S. military officer, San Diego set a lead to International Terrorism Operations Section 1 at FBI Headquarters and the JTTF in the Washington, D.C., Field Office (WFO). Five months later, WFO conducted an assessment of Hasan, who worked as a psychiatrist at the Walter Reed Army Medical Center. WFO queried certain FBI and Department of Defense (DoD) databases and reviewed the limited set of Army personnel records available to DoD personnel serving on JTTFs. […] Effective July 15, 2009, the Army assigned Hasan to the Darnall Army Medical Center at Fort Hood, Texas. In October 2009, the Army notified Hasan that he would be deployed to Afghanistan in November 2009. On November 5, 2009, Hasan entered the Fort Hood deployment center. He carried two pistols. He jumped on a desk and shouted 'Allahu Akbar!' - Arabic for 'God is great!' Then he opened fire, killing twelve U.S. soldiers and one DoD employee, and injuring forty-two others. The FBI immediately conducted an internal review of how San Diego and WFO handled Hasan's communications with Aulaqi. As a result of the review, the FBI took specific steps to improve its ability to detect and deter threats like Hasan. […] FBI Director Robert S. Mueller, III, determined that an additional, independent investigation of the FBI's actions was appropriate."
Federal Bureau of Investigation: http://www.fbi.gov/