PHNOM PENH, July 22, 2010 (AFP) - In January 1979, as the Khmer Rouge regime collapsed and its leaders fled Phnom Penh, invading Vietnamese troops stumbled upon an abandoned prison with fresh corpses chained to iron beds. It was Tuol Sleng, or "Hill of the Poisonous Trees", the most infamous of all of the jails run by Pol Pot's murderous regime.
Next week the prison's former chief Kaing Guek Eav, better known as Duch, will hear the verdict in his trial at a UN-backed tribunal where witnesses have recounted the horrors of a place from which almost no one came out alive.
Norng Chan Phal, 40, is one of just a handful of survivors to emerge from the Khmer Rouge regime's main torture centre, liberated by the Vietnamese invasion.
He told the trial last year how, as a child, he saw Tuol Sleng guards threaten, beat and photograph his mother. Soon afterwards she disappeared and was never seen again.
"I want Duch to be locked in prison for the rest of his life and forced to work farming in a prison field," Norng Chan Phal told AFP ahead of Monday's verdict. "I want him to feel what he did to others."
Prosecutors have demanded Duch, 67, be sentenced to 40 years in jail on charges of war crimes, crimes against humanity, premeditated murder and torture for overseeing the execution of some 15,000 prisoners.
Most were forced to confess as foreign spies and taken to a nearby killing field where executioners delivered a blow to the base of the neck with a steel club, then sliced their bellies open, former prison staff testified.
Duch, a former mathematics teacher, has said his orders were for all those imprisoned at Tuol Sleng to be killed to ensure "secrecy and security".
"No one was entitled to release them, (not) even Pol Pot," Duch said.
Prisoners at the interrogation centre, a former high school, suffered beatings, electric shocks to their genitals and had plastic bags tied over their heads, witnesses said during the nine-month trial.
One former Tuol Sleng guard even testified that many prisoners were drained of their blood.
The staff dared not refuse to work. Investigators estimate 200 of them even became prisoners there, facing certain execution.
Led by Pol Pot, who died in 1998, the Khmer Rouge emptied Cambodia's cities in a bid to forge a communist utopia. Up to two million people died of starvation, overwork and torture or were executed during the 1975-1979 regime.
Prosecutors assert Tuol Sleng, also known as S-21, was the regime's main killing apparatus among 198 prisons throughout Cambodia.
Duch has apologised for his past but many Cambodians doubt his sincerity since he consistently rejected allegations that he held a central leadership role in the Khmer Rouge, and said he never personally killed anyone.
These days the prison is a dilapidated genocide museum that displays mug shots of doomed inmates.
"Some people come here and when they see their parents in photos, they're shocked and collapse," said Chum Mey, 79, another survivor who now works as a tour guide at the museum.
Chum Mey testified that interrogators beat him for 12 days and nights as he pleaded for his life. He shuddered in pain after they pulled out his toenails, he said, and was subjected to electric shocks.
The agony finally ended when he falsely confessed to being a CIA and KGB agent, Chum Mey said, and his life was then spared because he was put to use repairing sewing machines and a water pump.
During Duch's trial, his defence team mostly focused on getting a lighter sentence, by downplaying his position within the regime and by highlighting his remorse, his time already served and his cooperation with the court.
Duch made further apologies for his crimes in a statement on the final day of arguments in November, but enraged many victims when he unexpectedly asked to be acquitted on the grounds he was not a senior member of the Khmer Rouge.