2 decades on, self-professed 9/11 mastermind awaits trial | Details

Khalid Shaikh Mohammed in a U.S. detention center in Guantanamo Bay. The difficulty in holding a trial is partly rooted in what the U.S. did with Khalid Shaikh Mohammed after his 2003 capture. Mohammed was waterboarded by CIA operatives - made to feel that he was drowning - 183 times. A senate investigation later concluded interrogations didn't lead to any valuable intelligence. Endless pretrial litigation over whether FBI reports can be used against the accused.