"Duch" is charged with crimes against humanity for his time as a prison commander under the regime.
Prosecutors read out the charges against Kaing Guek Eav, known as "Duch." He ran the SS-21 prison in Phnom Penh, the Cambodian capital, whose population was evacuated when the Khmer Rouge seized power in 1975. Duch is charged with committing crimes against humanity, war crimes, torture, and murder during four years as prison chief.
He spoke in court Monday only to acknowledge his identity and the charge sheet, which described how SS-21 was a death camp for known dissidents as well as a torture center used to extract confessions. Of the roughly 15,000 prisoners sent there, only a handful survived.
"I have already been notified of the charges against me," Duch told the court, according to Agence France-Presse. "Before I was arrested by the military court, I was a teacher."
A defense lawyer for Duch said he would be allowed to address the court later this week. Administrative hearings were held in February, but Monday began the first significant part of the trial. The war crimes tribunal is a hybrid Cambodian-international body based on French law that has so far cost $143 million and has attracted criticism for slow progress on trying suspects.
In his trial, Duch is likely to implicate his fellow cadre, who have denied all the charges and have sought to blame foreign powers for the killings. He cooperated fully with the investigating judges probing the grisly events at SS-21, a former school that is now a museum of torture.