The commission did not have a mandate to investigate how detainees were treated; our role was to investigate the history and evolution of Al Qaeda and the 9/11 plot. Beginning in June 2003, we requested all reports of intelligence information on these broad topics that had been gleaned from the interrogations of 118 named individuals, including both Abu Zubaydah and Abd al Rahim al-Nashiri, two senior Qaeda operatives, portions of whose interrogations were apparently recorded and then destroyed.

The C.I.A. gave us many reports summarizing information gained in the interrogations. But the reports raised almost as many questions as they answered. Agency officials assured us that, if we posed specific questions, they would do all they could to answer them.

So, in October 2003, we sent another wave of questions to the C.I.A.’s general counsel. One set posed dozens of specific questions about the reports, including those about Abu Zubaydah. A second set, even more important in our view, asked for details about the translation process in the interrogations; the background of the interrogators; the way the interrogators handled inconsistencies in the detainees’ stories; the particular questions that had been asked to elicit reported information; the way interrogators had followed up on certain lines of questioning; the context of the interrogations so we could assess the credibility and demeanor of the detainees when they made the reported statements; and the views or assessments of the interrogators themselves.

The general counsel responded in writing with non-specific replies. The agency did not disclose that any interrogations had ever been recorded or that it had held any further relevant information, in any form. Not satisfied with this response, we decided that we needed to question the detainees directly, including Abu Zubaydah and a few other key captives.

In a lunch meeting on Dec. 23, 2003, George Tenet, the C.I.A. director, told us point blank that we would have no such access. During the meeting, we emphasized to him that the C.I.A. should provide any documents responsive to our requests, even if the commission had not specifically asked for them. Mr. Tenet replied by alluding to several documents he thought would be helpful to us, but neither he, nor anyone else in the meeting, mentioned videotapes.