Close-up on Comrade Duch
Irish photo journalist Nic Dunlop was the man responsible for tracking down the commandant of Cambodia's notorious Khmer Rouge torture camp.
As a young man Nic became fascinated by the story of the Killing Fields and the bloody history of Cambodia.
And ten years ago, almost by chance, he discovered Comrade Duch living in a village and working as a teacher.
Nic confronted the former Khmer Rouge official, who went on to confess his crimes to him and express remorse.
Comrade Duch was finally tried for his crimes this year - a trial which has now ended and is awaiting verdict.
During the trial, Nic says he saw a man who seemed disconnected from reality.
Nic Dunlop spoke to Matthew Bannister and described meeting Comrade Duch, who, he says, remains enigmatic.
He said, "he was always very diligent, always on time, he helped students whenever they were having difficulties - generally the complete antithesis of this fearful figure that ran this terrifying torture camp."
The Lost Executioner by Nic Dunlop is published by Bloomsbury