It was a dangerous place to work. As many as one-third of the prison staff was executed, sometimes for torturing with too much enthusiasm and letting a prisoner die.

Duch, with his tiny eyes and prominent ears, came to symbolize for me the cold, impersonal cruelty of a movement that lived by the slogan, “To keep you is no gain, to destroy you is no loss.”

I had arrived in Cambodia in 1996, when the country was still ragged and panting from the ravages of four years of mass killing, followed by more than a decade of civil war as the Khmer Rouge returned to their jungle insurgency.

I had seen trauma before, but never an entire traumatized nation. I reminded myself regularly that all the adults I met were survivors or former killers, who now had to try to live with what they had seen or done. Almost everyone, survivor or killer, had lost family members. They carried around inside themselves millions of tiny worlds of suffering.

I visited land mine victims from the civil war in the military hospital, a dark and dreadful place without regular water or electricity, where men begged me for crutches.

Others, crippled and rejected by society, hopped around the central market seeking alms. Of all of them, it was one man whose stark words stay with me. Holding out his hat to me, he said simply, naming the region where he had lost his leg, “Battambang — boom!”