Have you heard the screams of a prisoner who is being tortured in America's war on terror? I can't forget them.

They pierced the walls of a detention center I visited in Samarra during an offensive by American and Iraqi forces in 2005. In a small room, I was interviewing a frightened detainee whose head was bandaged from an injury he unconvincingly attributed to a car accident during his capture. Bloodstains dripped down the side of a desk, and there was an American military adviser with us, as well as a portly officer of Iraq's special police commandos.

Suddenly there was a chilling scream....