The CIA has admitted it destroyed at least two tapes documenting the interrogations of two prisoners held at a secret CIA prison. The American Civil Liberties Union accused the CIA of deliberately destroying evidence that could have been used to hold CIA agents accountable for the torture of prisoners. One of the tapes is believed to have shown CIA agents waterboarding the al-Qaeda operative Abu Zubaydah. CIA Director Michael Hayden said the tapes were destroyed because they posed a “serious security risk.” He said that if they were to become public they would have exposed CIA officials and their families to “retaliation from Al Qaeda and its sympathizers.” Human rights groups say the videotapes could have led to criminal prosecution of the CIA agents involved for torture and abuse. The CIA had previously refused to provide the recordings to members of the Sept. 11 Commission or a federal judge in the Zacarias Moussaoui case. The former general counsel for the 9/11 Commission, Daniel Marcus, said the destruction of the tapes could amount to obstruction to withhold evidence being sought in a criminal or fact-finding investigation.