Washington, D.C. ? The CIA destroyed a dozen videotapes of harsh interrogations of terror suspects, according to documents filed Friday in a lawsuit over the government’s treatment of detainees.

The 12 tapes were part of a larger collection of 92 videotapes of terror suspects that the CIA destroyed. The extent of the tape destruction was disclosed through a suit filed by the American Civil Liberties Union against the government.

Heavily redacted papers filed in the case indicate a dozen destroyed tapes show so-called “enhanced interrogation techniques.”

The CIA’s enhanced interrogation methods are secret, but they once included waterboarding, which simulates drowning.