Nhem En will be asked to testify against former Khmer Rouge bosses at their crimes-against-humanity trial in Cambodia. Nhem En had a unique job -- photographing the arrivals at Tuol Sleng prison in Phnom Penh, knowing they almost certainly wouldn't leave alive.

From the Oct. 26 NYT article:

He had a job to do, and he did it supremely well, under threat of death, within earshot of screams of torture: methodically photographing Khmer Rouge prisoners and producing a haunting collection of mug shots that has become the visual symbol of Cambodia’s mass killings.

“I’m just a photographer; I don’t know anything,” he said he told the newly arrived prisoners as he removed their blindfolds and adjusted the angles of their heads. But he knew, as they did not, that every one of them would be killed.

“I had my job, and I had to take care of my job,” he said in a recent interview. “Each of us had our own responsibilities. I wasn’t allowed to speak with prisoners.”

That was three decades ago, when the photographer, Nhem En, now 47, was on the staff of Tuol Sleng prison, the most notorious torture house of the Khmer Rouge regime, which caused the deaths of 1.7 million people from 1975 to 1979.

This week he was called to be a witness at a coming trial of Khmer Rouge leaders, including his commandant at the prison, Kaing Geuk Eav, known as Duch, who has been arrested and charged with crimes against humanity.

The trial is still months away, but prosecutors are interviewing witnesses, reviewing tens of thousands of pages of documents and making arrests.

As a lower-ranking cadre at the time, Mr. Nhem En is not in jeopardy of arrest. But he is in a position to offer some of the most personal testimony at the trial about the man he worked under for three years.

In the interview, Mr. Nhem En spoke with pride of living up to the exacting standards of a boss who was a master of negative reinforcement.

“It was really hard, my job,” he said. “I had to clean, develop and dry the pictures on my own and take them to Duch by my own hand. I couldn’t make a mistake. If one of the pictures was lost I would be killed.”

But he said: “Duch liked me because I’m clean and I’m organized. He gave me a Rolex watch.”

Here's an earlier post with much stuff on Tuol Sleng.