But nearly four months after the disclosure that the tapes were destroyed, the list of legal entanglements for the CIA, the Defense Department and other agencies is only growing longer. In addition to criminal and Congressional investigations of the tapes’ destruction, the government is fighting off challenges in several major terrorism cases and a raft of prisoners’ legal claims that it may have destroyed evidence.

“They thought they were saving themselves from legal scrutiny, as well as possible danger from Al Qaeda if the tapes became public,” said Frederick P Hitz, a former CIA officer and the agency’s inspector general from 1990 to 1998, speaking of agency officials who favored eliminating the tapes. “Unknowingly, perhaps, they may have created even more problems for themselves.”

In a suit brought by Hani Abdullah, a Yemeni prisoner at Guantánamo Bay, Cuba, a federal judge has raised the possibility that, by destroying the tapes, the CIA violated a court order to preserve all evidence relevant to the prisoner. In at least 12 other lawsuits, lawyers for prisoners at Guantánamo and elsewhere have filed legal challenges citing the CIA tapes’ destruction, said David H. Remes, a Washington lawyer representing 16 prisoners.

“This is like any other cover-up,” Remes said. “We’ve only scratched the surface.”

Plans for the possible prosecution of another prisoner, Ali al-Marri, who has been held since 2003 in a naval brig in Charleston, SC, could be in jeopardy after the Pentagon recently revealed that it had destroyed some tapes of Marri’s interrogation. Other tapes showing rough treatment of Marri, which were discovered in a Pentagon review ordered after the CIA revelations and have been preserved, could prove embarrassing if presented at his trial.

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.