A Senate Democratic leader said Sunday the attorney general should appoint a special counsel to investigate the CIA's destruction of videotaped interrogations of two suspected terrorists.

Sen. Joe Biden, a Democratic presidential candidate and chairman of the Senate Foreign Affairs Committee, cited Michael Mukasey's refusal during confirmation hearings in October to describe waterboarding as torture.

Mukasey's Justice Department and the CIA's internal watchdog announced Saturday they would conduct a joint inquiry into the matter. That review will determine whether a full investigation is warranted.

"He's the same guy who couldn't decide whether or not waterboarding was torture and he's going to be doing this investigation," said Biden, who noted that he voted against making Mukasey the country's top law enforcer.

"I just think it's clearer and crisper and everyone will know what the truth ... if he appoints a special counsel, steps back from it," said Biden, D-Del.

"I think the easiest, straightest thing to do is to take it out of the political realm, appoint a special prosecutor and let them decide, and call — call it where it is. Is there a criminal violation? If there is, proceed. If not, don't," the senator said.

The spy agency's director, Michael Hayden, told CIA employees Thursday that the recordings were destroyed out of fear the tapes would leak and reveal the identities of interrogators. He said the sessions were videotaped to provide an added layer of legal protection for interrogators using new, harsh methods authorized by President Bush as a way to break down the defenses of recalcitrant prisoners.

The House and Senate intelligence committees also are investigating.

The White House was scrambling over the weekend to determine who in the administration knew about the tapes and when. That includes Harriet Miers, who was a deputy White House chief of staff in 2003. Miers became White House counsel in early 2005; she left that job in January.

"I think that Hayden is not to be the judge of whether or not his ordering or his condoning the destroying of the tapes was lawful," Biden said. "It appears as though there may be an obstruction of justice charge here, tampering with evidence, and destroying evidence. And this is — I think this is one case where it really does call for a special counsel. I think this leads right into the White House. There may be a legal and rational explanation, but I don't see any on the face of it."

Bush "has no recollection" of hearing about either the tapes' existence or their destruction before being briefed about it Thursday morning, White House press secretary Dana Perino has said. She also said the president has "complete confidence" in Hayden's handling of the matter

Waterboarding is a harsh interrogation technique that involves strapping down a prisoner, covering his mouth with plastic or cloth and pouring water over his face. The prisoner quickly begins to inhale water, causing the sensation of drowning.

Mukasey's refusal to define waterboarding as torture came in response to senators' questions about the CIA's alleged use of the technique. Hayden, who took over at the CIA in 2006, that year prohibited the use of waterboarding in CIA interrogations. Torture is illegal both under U.S. and international law.

The tapes showed interrogations of Abu Zubaydah, the first high-value detainee taken by the CIA in 2002. Zubaydah, under harsh questioning, told CIA interrogators about alleged Sept. 11 accomplice Ramzi Binalshibh. The two men's confessions also led to the capture of Khalid Sheikh Mohammed, who the U.S. government said was the mastermind behind the Sept. 11 terrorist attacks.

The other taped interrogations showed Abd al-Rahim al-Nashiri, the alleged mastermind of the 2000 attack on the USS Cole, which left 17 U.S. sailors dead. He and Zubaydah are now being held at Guantanamo Bay.

Biden spoke on "This Week" on ABC.