WASHINGTON — A Central Intelligence Agency inspector general’s report set to be released Monday provides new details about abuses that took place inside the agency’s secret prisons, including details of how C.I.A. officers carried out mock executions and threatened at least one prisoner with a gun and a power drill.

C.I.A. jailers at different times held the handgun and the drill close to the detainee, Abd al-Rahim al-Nashiri, threatening to harm him if he did not cooperate with his interrogators, a government official familiar with the contents of the report said.

Mr. Nashiri, who was implicated in the bombing of the Navy destroyer Cole in 2000, was one of two C.I.A. detainees whose interrogation sessions were videotaped — tapes that were destroyed by C.I.A. officers in 2005. It is unclear whether the threats with the gun and the power drill were documented on the tapes.

In a separate episode detailed in the report — completed in 2004 by the inspector general, John L. Helgerson, but emerging now after a lawsuit by the American Civil Liberties Union forced its release — C.I.A. officers fired a gunshot in a room next to a detainee, leading the prisoner to believe that a second detainee had been killed.

It is a violation of the federal torture statute to threaten a detainee with imminent death.

The C.I.A. declined to comment on specifics of the report, which were first reported Friday evening by Newsweek.

Paul Gimigliano, a C.I.A. spokesman, said: “The C.I.A. in no way endorsed behavior — no matter how infrequent — that went beyond the formal guidance. This has all been looked at; professionals in the Department of Justice decided if and when to pursue prosecution.”

A federal prosecutor is now investigating the destruction of the C.I.A. tapes, but the Justice Department has thus far declined to open a formal investigation into the abuses in C.I.A. prisons.

That may be about to change, as Attorney General Eric H. Holder Jr. is considering whether to appoint a prosecutor to examine the allegations in Mr. Helgerson’s report, and to investigate a number of cases where detainees died in C.I.A. custody.

President Obama has insisted that C.I.A. officers who adhered to Justice Department interrogation guidelines should escape prosecution, and Mr. Holder is not expected to single out Justice Department lawyers who approved the brutal interrogation techniques.

This would give any future investigation a somewhat narrow mandate: aiming only at C.I.A. officers who carried out abuses that exceed the interrogation guidelines.

Mr. Helgerson’s report is said to document in grim detail a number of abuse cases, and its release on Monday is likely to reinvigorate a partisan debate on Capitol Hill.

Even as White House officials say that they are hesitant to dwell on the detainee abuse during the Bush administration, the A.C.L.U. lawsuit has forced officials to make public a number of classified documents from that era.

Besides the inspector general’s report, other documents expected to be released Monday are a 2007 Justice Department memo reauthorizing the C.I.A.’s “enhanced” interrogation techniques, documents that former Vice President Dick Cheney has said provide evidence that the interrogation methods produced valuable information about Al Qaeda; and Justice Department memos from 2006 concerning conditions of confinement in C.I.A. jails.

In Mr. Nashiri’s case, military prosecutors announced in July 2008 that they would seek the death penalty as they brought war crimes charges against him. He has been held at the prison camp in Guantánamo Bay, Cuba, and is suspected of helping to plan the bombing of the Cole, an attack that killed 17 sailors.

Mr. Nashiri is a Saudi who has long been described by American officials as Al Qaeda’s operations chief in the Persian Gulf and the primary planner of the October 2000 attack on the Cole.

Mr. Nashiri is one of three detainees who the C.I.A. has acknowledged were subjected to waterboarding. Mr. Nashiri was interrogated in the agency’s secret prisons before he was transferred to Guantánamo in 2006.

In announcing the charges, which will be heard by the Bush administration’s military commission tribunals at Guantánamo, the Pentagon official, Brig. Gen. Thomas W. Hartmann, appeared to back away from years of assertions by American officials about Mr. Nashiri when he was asked at a news conference if Mr. Nashiri was suspected of being the primary planner or mastermind of the Cole attack.

“I’m not going to say either of those,” General Hartmann said. “I’m going to say he helped to plan and organize and direct the attacks.”

By MARK MAZZETTI