Matthew Alexander led an interrogations team assigned to a Special Operations task force in Iraq in 2006. He is the author of "How to Break a Terrorist: The U.S. Interrogators Who Used Brains, Not Brutality, to Take Down the Deadliest Man in Iraq." He is writing under a pseudonym for security reasons.
The Washington Post published a summary under the title "I'm Still Tortured by What I Saw in Iraq":
I should have felt triumphant when I returned from Iraq in August 2006. Instead, I was worried and exhausted. My team of interrogators had successfully hunted down one of the most notorious mass murderers of our generation, Abu Musab al-Zarqawi, the leader of al-Qaeda in Iraq and the mastermind of the campaign of suicide bombings that had helped plunge Iraq into civil war. But instead of celebrating our success, my mind was consumed with the unfinished business of our mission: fixing the deeply flawed, ineffective and un-American way the U.S. military conducts interrogations in Iraq. I'm still alarmed about that today. (Full)
Picture courtesy Imagination Manifesto