Omar Abdel-Rahman
According to statements by Lt. Col. Anthony Shaffer and those of four others, Able Danger had identified two of three al-Qaeda cells active in the 9/11 attacks; the 'Brooklyn cell' linked to "Blind Sheik" Omar Abdel-Rahman, including September 11 attacks leader Mohamed Atta, and three of the 9/11 plot's other 19 hijackers.