Speaking in English, Mohammed “seemed to relish the opportunity, sometimes for hours on end, to discuss the inner workings of al-Qaeda and the group’s plans, ideology and operatives,” said one of two sources who described the sessions, speaking on the condition of anonymity because much information about detainee confinement remains classified. “He’d even use a chalkboard at times.”

These scenes provide previously unpublicized details about the transformation of the man known to U.S. officials as KSM from an avowed and truculent enemy of the United States into what the CIA called its “preeminent source” on al-Qaeda. This reversal occurred after Mohammed was subjected to simulated drowning and prolonged sleep deprivation, among other harsh interrogation techniques…

Over a few weeks, he was subjected to an escalating series of coercive methods, culminating in 7 1/2 days of sleep deprivation, while diapered and shackled, and 183 instances of waterboarding. After the month-long torment, he was never waterboarded again.

“What do you think changed KSM’s mind?” one former senior intelligence official said this week after being asked about the effect of waterboarding. “Of course it began with that.”

Mohammed, in statements to the International Committee of the Red Cross, said some of the information he provided was untrue…

One former U.S. official with detailed knowledge of how the interrogations were carried out said Mohammed, like several other detainees, seemed to have decided that it was okay to stop resisting after he had endured a certain amount of pressure.

“Once the harsher techniques were used on [detainees], they could be viewed as having done their duty to Islam or their cause, and their religious principles would ask no more of them,” said the former official, who requested anonymity because the events are still classified. “After that point, they became compliant. Obviously, there was also an interest in being able to later say, ‘I was tortured into cooperating.'”