The prison had a debriefing room, where Mohammed, who saw himself as something of a professor, held “office hours,” as he told CIA officers. While chained to the floor, Mohammed would lecture the CIA officers on his path to jihad, his childhood and family. Tea and cookies were served.

Along with the other five detainees at the prison in Bucharest, Mohammed was given assignments about his knowledge of al-Qaida, or “homework,” as CIA officers called it. He was given Snickers candy bars as rewards for his studiousness.

In Romania, the prison provided books for detainees to read. Mohammed, former officials said, enjoyed the Harry Potter series. For the CIA officers at the prison, not so much. For security reasons, after a prisoner finished a book, they tediously checked every page to ensure detainees weren’t passing messages. They once caught Mohammed trying to hide a message in a book warning his prison mates not to talk about Osama bin Laden’s courier.

Mohammed graduated from North Carolina AT&T State University with a degree in mechanical engineering in 1986. It’s not clear whether Mohammed was interested in designing a better vacuum or had ulterior motives.