A former American army torturer has laid bare the traumatic effects of American interrogation techniques in Iraq - on their victims and on the perpetrators themselves. Tony Lagouranis conducted mock executions, forced men and boys into agonising stress positions, kept suspects awake for weeks on end, used dogs to terrify detainees and subjected others to hypothermia. But he confesses that he was deeply scarred by the realisation that what he did has contributed to the downfall of American forces in Iraq. Mr Lagouranis, 37, suffered nightmares and anxiety attacks on his return to Chicago. Between January 2004 and January 2005, he tortured suspects, most of whom he says turned out to be innocent. He says that he realised he had entered a moral dungeon when he found himself reading a Holocaust memoir, hoping to pick up torture tips from the Nazis. When I first got back I had a lot of anxiety. I had a personal crisis because I felt I had done immoral things and I didn't see a way to cope with that. I saw a psychologist. I had a lot to work through." He says that helped prevent him becoming "a totally broken human being". Mr Lagouranis has written a recently published book about his experiences, Fear Up Harsh, a term for intimidating a detainee by shouting at him. He makes clear that torture has cost America its moral authority in Iraq by detaining innocent people and treating them badly. He writes: "My actions, combined with the actions of the arresting infantry who left bruises on their prisoners, and the actions of the officers who wanted to get promotions, repeated in microcosm all over this country, had a cumulative effect. I could blame Bush and Rumsfeld, but I would always have to also blame myself."