The methods were not mentioned in Justice Department memos authorizing the so-called enhanced interrogation program for terrorism detainees.

    Washington - The CIA staged a mock execution and brandished weapons, including a gun and a power drill, during interrogation sessions with detainees, according to a long-secret internal CIA report expected to be released Monday.

    The episodes are part of a catalog of alleged abuses -- a 2004 report by the CIA's inspector general -- that has prompted Atty. Gen. Eric H. Holder Jr. to consider appointing a criminal prosecutor to investigate cases in which the CIA strayed beyond its authorities.

    The prisoner confronted with the gun and drill was identified by current and former U.S. officials as Abd al Rahim al Nashiri, the alleged plotter of the attack on the U.S. destroyer Cole. Nashiri was also one of three prisoners who was subjected to waterboarding, the simulated drowning method.

    The inspector general's report also describes at least one instance in which the CIA fired a gun in a room next door to a detainee in an apparent effort to convince the prisoner that another terrorism suspect had been executed, officials said.

    Some of the allegations, including the presence of a gun in an interrogation room, have been previously reported. But some of the details disclosed this weekend, including the name of the detainee, are new.

    The CIA officer who brandished the gun was removed from the program and reprimanded.

    The cases are among the most extreme examples in which CIA interrogators sought to improvise methods not mentioned in the legal memos the agency procured from the Justice Department authorizing the so-called enhanced interrogation program.

    "Some of the things that were done were almost in juvenile detective mode," said a former U.S. official familiar with the report, who spoke on condition of anonymity because of the issue's sensitivity.

    Even so, the report focused most of its strongest criticism on alleged abuses of interrogation methods that the agency had been explicitly authorized to use. In particular, the report raised troubling questions about the frequency with which certain prisoners were being waterboarded.

    Segments of the report that were declassified this year indicate that two senior Al Qaeda prisoners, Khalid Shaikh Mohammed and Abu Zubaydah, were waterboarded a total of 266 times between them, far more than had been envisioned in Justice Department memos that gave the CIA permission to use the method.

    The CIA declined to discuss specifics in the report.

    But CIA spokesman Paul Gimigliano said that the Justice Department has had the report since 2004 and that prosecutors have carefully reviewed it for legal accountability. He said the CIA "in no way condoned behavior -- no matter how infrequent -- that went beyond formal guidance."

    "This has all been looked at," he added. "Professionals in the Department of Justice decided if and when to pursue prosecution. That's how the system was supposed to work and that's how it did work."

    Still, Holder is said to be moving closer to appointing a prosecutor to examine allegations of CIA abuses. The disclosure of fresh details from the report this weekend was seen by some in Washington as a sign that Holder may be setting the stage for such an announcement.

    The details on the mock execution and the use of the drill were first reported online Friday by Newsweek. The CIA's use of a gun in the booth with a prisoner was first disclosed in The Times this month.