From The Youtuber http://www.youtube.com/user/Irancontrascumdid911
Special Agent John O'Neill was Deputy Director of the FBI under Louis Freeh from 1997 to 1999. His specialty: Tracking al-Qaeda. In the months prior to 9/11 he sent evidence of the impending attacks, along with important information about the suspects who were planning on carrying it out, up through the chain of command and was met with nothing but resistance and attempts to ruin his credibility. Frustrated with this, O'Neill had gone public, stating that he was ordered not to investigate Saudi/al-Qaeda connections because of the Enron pipeline deal.
O'Neill then left the FBI and began working as head of security at the World Trade Center, which reportedly offered him double [some reports say triple] his current FBI salary. His first day was September 11th, 2001. He was the man taking over for the complex's then security-head, Marvin Bush [the President's brother] whose company, Securacom [a.k.a. Stratesec], happened to be in charge of security for United Airlines, as well as the security detail at Dulles International Airport, from which American Airlines Flight 77 that allegedly hit the Pentagon had originated that morning.
O'Neill was on the 34th floor of the North Tower when the first plane hit. He had evacuated the building and was last seen alive by fellow FBI agent Wesley Wong outside the South Tower about 15 minutes before it collapsed. His uncharred body would be found weeks later under a stairwell of that same building. John O'Neill --the Man who Knew--was dead at age 49.