The CIA promised the prisoners freedom, safety for their families and millions of dollars from the agency's secret accounts.
It was a risky gamble. Officials knew there was a chance that some prisoners might quickly spurn their deal and kill Americans.
For the CIA, that was an acceptable risk in a dangerous business. For the American public, which was never told, the programme was one of the many secret trade-offs the government made on its behalf.
The programme was carried out in a secret facility built a few hundred yards from the administrative offices of the prison in Guantanamo Bay, Cuba. The eight small cottages were hidden behind a ridge covered in thick scrub and cactus.
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The programme and the handful of men who passed through these cottages had various official CIA code names.
But those who were aware of the cluster of cottages knew it best by its sobriquet: Penny Lane.
Nearly a dozen current and former US officials described aspects of the programme to The Associated Press. All spoke on condition of anonymity because they were not authorised to discuss the secret program publicly by name, even though it ended in about 2006.
Some of the men who passed through Penny Lane helped the CIA find and kill many top al-Qaeda operatives, current and former US officials said. Others stopped providing useful information and the CIA lost touch with them.