WASHINGTON - Standing naked, except for a hood covering their heads, sleep deprivation, insult slaps, water dousing and walling, or slamming a detainees head against a wall, were techniques used by CIA interrogators to break detainees, according to a media report, citing an agency memo. The memo, sent to the US Justice Departments Office of Legal Counsel on December 30, 2004, was released on Monday under a Freedom of Information Act lawsuit filed by Amnesty International USA and the American Civil Liberties Union. US Attorney General Eric Holder on Monday named a special prosecutor to probe Central Intelligence Agency (CIA) prisoner abuse cases. His decision, which promises political headaches for President Barack Obama, came after the Justice Departments ethics watchdog recommended considering prosecution of CIA employees or contractors for interrogations in Iraq and Afghanistan that went beyond approved limits. The goal of interrogation is to create a state of learned helplessness and dependence conducive to the collection of intelligence, the memo, outlining procedures for handling captured al-Qaeda leaders sent to CIA black site prisons, said. The document, reported by The Washington Post, said prior to an interrogation session, detainees may be stripped and held in a vertical shackling position to begin sleep deprivation. Once the interrogation begins, the insult slap on the face may be used when the interrogator needs to immediately correct the detainee, the memo said. The document said walling was one of the most effective interrogation techniques for wearing down detainees physically. An HVD (high-value detainee) may be walled one time (one impact with the wall) to make a point or 20 to 30 times consecutively when the interrogator requires a more significant response to a question, the document said. Interrogations at CIA prisons occurred in special cells outfitted on one side with a plywood wall to prevent severe head injuries, The Washington Post reported. The paper said agency spokesman George Little noted that the interrogation program operated under guidelines approved by top legal officials of the Bush administration. This program, which always constituted a fraction of the CIAs counterterrorism efforts, is over, Little was quoted as saying. CIA officials have also noted that harsh techniques were reserved for a small group of top-level terrorism suspects believed to be knowledgeable about the September 11, 2001, attacks, the Post said. Former US Vice President Dick Cheney criticized Obamas ability to handle national security after the special prosecutor was appointed. Cheney, who has emerged as a vocal defender of Bush administration policies since leaving the White House, said the intelligence obtained from harsh interrogation techniques had saved lives. The people involved deserve our gratitude. They do not deserve to be the targets of political investigations or prosecutions, he said in a statement.