WASHINGTON (CNN) -- Federal prosecutors will investigate the destruction of CIA videotapes showing agents interrogating terrorism suspects, Attorney General Michael Mukasey said Wednesday.
Lawyers for several Guantanamo detainees say the government has defied orders to preserve evidence.
Prosecutors and FBI agents will try to determine whether laws were broken. A preliminary inquiry found enough evidence to pursue possible criminal charges.
The CIA said last month it videotaped the questioning of al Qaeda suspects Abu Zubaydah and Abd al-Rahim al-Nashiri in 2002.
The tapes reportedly showed rough interrogation techniques, including the use of "waterboarding," which simulates drowning.
Mukasey said he has appointed John Durham, a prosecutor from the U.S. attorney's office in Connecticut, to lead the investigation.
The U.S. attorney for the Eastern District of Virginia, home of the CIA, typically would investigate, but Mukasey said he tapped Durham because federal prosecutors in the Virginia district already are investigating the intelligence community.
The CIA "will of course cooperate fully with this investigation as it has with the others into this matter," said Mark Mansfield, a spokesman for the agency.
CIA Director Michael Hayden said the tapes were destroyed in 2005 because national security could have been compromised by revealing the identities of the interrogators.
The administration argues the tapes of the two interrogations were technically not covered by a judge's order to preserve "all evidence and information regarding the torture, mistreatment, and abuse of detainees now at the United States Naval Base at Guantanamo Bay" because Zubaydah and al-Nashiri were not held at Guantanamo at the time of the order.
But lawyers for several other Guantanamo prisoners fighting their detention in federal courts said the government defied similar orders to preserve evidence that could clear their clients of wrongdoing.
News of the investigation came as the chairman of the 9/11 commission repeated assertions the CIA hindered the panel's inquiry by not disclosing the tapes' existence.
Chairman Thomas Kean, a Republican, and Co-Chairman Lee Hamilton, a Democrat, wrote that they asked for "the kind of information that would have been contained in such videotapes" but that "no one in the administration ever told the commission" about the tapes.
"Those who knew about those videotapes -- and did not tell us about them -- obstructed our investigation," they wrote.
But a CIA spokesman fired back that Kean and Hamilton were "simply wrong" to say the intelligence agency had obstructed the 9/11 commission.
"The fact of the matter is that the CIA went to great lengths to meet the requests of the 9/11 commission and provided the commission with a wealth of information," George Little said.
At the White House, spokesman Tony Fratto said the administration continues "to support the attorney general's investigation."
In addition to the Justice Department's criminal investigation, the House Intelligence Committee and the Senate Intelligence Committee are looking into the tapes' destruction.
Members of the House Intelligence Committee reviewed records at CIA headquarters about two weeks ago. The committee also wants to hear from two officials: Jose Rodriguez, who led the CIA's clandestine service; and John Rizzo, the agency's acting general counsel.
Two key members of the Senate Judiciary Committee who opposed Mukasey's nomination indicated they are satisfied with his decision to proceed without formal appointment of an independent special counsel.
"We see that the department's initial investigation has led him to determine that it is necessary to appoint an outside prosecutor to bring a criminal investigation," said committee Chairman Patrick Leahy, D-Vermont.
The move "shows that many of us were right to be concerned with possible obstruction of justice and obstruction of Congress," he added
Sen. Edward Kennedy, D-Massachusetts, said, "Today's announcement by the Department of Justice is an important step towards a full and independent investigation of the CIA's destruction of interrogation tapes."
But other lawmakers said Mukasey hasn't gone far enough.
"It is disappointing that the attorney general has stepped outside the Justice Department's own regulations and declined to appoint a more independent special counsel in this matter," said House Judiciary Committee Chairman John Conyers, D-Michigan.
"Nothing less than a special counsel with a full investigative mandate will meet the tests of independence, transparency and completeness," he said.
Sen. Joe Biden of Delaware, a presidential candidate and member of the Senate Judiciary Committee, said the attorney general should have appointed an independent special prosecutor rather than a prosecutor who reports to the Justice Department. E-mail to a friend