In a letter to the C.I.A. on Saturday, Assistant Attorney General Kenneth L. Wainstein, who heads the Justice Department’s National Security Division, requested to meet with Mr. Helgerson and Mr. Rizzo early next week to discuss the inquiry.

Mr. Rodriguez, who could not be reached for comment, announced his retirement from the agency this summer. The New York Times has made a request through an agency spokesman to speak with him.

Officials have acknowledged that the destruction of evidence like videotaped interrogations could raise questions about whether the C.I.A. was seeking to hide evidence of coercion. A review of records from military tribunals indicates that five lower-level detainees at Guantánamo Bay, Cuba, were initially charged with offenses based on information provided by or related to Abu Zubaydah.

Military defense lawyers said the fact that interrogation tapes were destroyed could provide a way to challenge other cases that may be based on information from Abu Zubaydah, though such challenges would face major legal obstacles under the current rules for military prosecutions. They said the defense could argue that the tapes might have raised questions about whether the information was believable or whether Abu Zubaydah had invented it simply to stop aggressive interrogation techniques. Col. Steven David, the chief military defense lawyer for the Guantánamo war crimes cases, said at a trial, “The inference is they destroyed it because it was bad for them.”

He said the disclosure of the destroyed tapes “raises serious concerns” about other potential prosecutions, but it was too early to say how many, or how serious the damage might be. In any case based on information from Abu Zubaydah, defense lawyers could raise the issue of the destroyed tapes as a way to challenge the case. From a defense lawyer’s perspective, Colonel David said, “the issue becomes what is lost, what is destroyed, what else has been destroyed and what else is out there that we are not aware of.”

Abu Zubaydah and Mr. al-Nashiri, who is said to be the chief planner of the 2000 attack on the Navy destroyer Cole, are the only suspected Qaeda figures identified so far as the subjects of interrogations recorded on the destroyed tapes.

The destruction of the tapes has intensified the focus on Abu Zubaydah, who was captured in March 2002. As one of the first close associates of Osama bin Laden to be caught after the 9/11 attacks, Abu Zubaydah became a test case on which the C.I.A. built and then adjusted its program of aggressive interrogations and overseas secret jails in the years that followed.