The destruction of tapes has also prompted challenges from lawyers for Zacharias Moussaoui, the convicted Qaeda operative who had unsuccessfully sought testimony at his trial from Abu Zubaydah, one of the two Qaeda suspects whose interrogation videotapes were destroyed in November 2005. At that time, a defense motion seeking records of Abu Zubaydah’s interrogation was pending before a federal court in Virginia.

This motion in the Moussaoui case, among other legal challenges, has raised questions about a statement in December by the C.I.A. director, Gen. Michael V. Hayden, that he understood the tapes were destroyed only after it was determined that they were “not relevant to any internal, legislative, or judicial inquiries.”

Officially, the CIA has said that the tapes were destroyed primarily because of concerns that their public exposure could endanger the safety of C.I.A. officers. But in interviews in recent months with several officers involved in the decision, they said that a primary factor was the legal risks that officers shown on the tape might face.

Despite all the legal complications, those in the CIA who got rid of the videotapes may have achieved one of their presumed goals: preventing a torture prosecution, said Deborah Colson, a senior associate at Human Rights First.

“It may be impossible to reconstruct any criminal conduct that was caught on the tapes,” Colson said.