Comrade Duch, a former senior figure of the Khmer Rouge convicted of crimes against humanity in Cambodia, has died.
He was serving a life term after being sentenced by a UN-backed court.
Kaing Guek Eav, known as Comrade Duch, ran the notorious Tuol Sleng prison where thousands of people were tortured and murdered in the late 1970s.
As many as two million people are believed to have died under the Khmer Rouge, a Maoist regime that controlled Cambodia from 1975 to 1979.
In 2010, Duch became the first senior Khmer Rouge leader to be convicted by the UN-backed tribunal after a journalist found him in hiding a decade earlier. He was sentenced in 2012.
He died on Wednesday, aged 77, a spokesman for the tribunal in the capital Phnom Penh said, without giving details of the cause. He had been ill for many years.
“Duch died this morning at 00:52am, on 2 September at Khmer Soviet Friendship Hospital. Details of what he died of, I can’t tell,” the spokesman said.
Duch’s testimony at the tribunal was a landmark moment for Cambodians who had suffered under the Khmer Rouge’s brutal reign, and future generations.
While prison chief at Tuol Sleng, Duch maintained a huge archive of photos and documents, including thousands of prisoner “confessions”, that revealed many aspects of the Khmer Rouge’s inner workings. They also helped prosecutors trace the final months of thousands of inmates’ lives.
In Phnom Penh, there were mixed feelings about his death.
“If he stayed alive then we may still hear more of the history from him for the younger generation and people,” one man told Reuters news agency.
Another resident said that she would never forget his crimes. “He deserves to serve more prison terms. But now he has died, I can forgive him and his case is finished.”