In Cambodia, the Khmer Rouge tribunal is providing fresh insights about Pol Pot's bloody regime.
The trial of Kang Guek Eav, also known as Duch, has gone into recess after testimony that ultimate responsibility for death camps like S-21 lay with Nuon Chea. Known as Brother Number Two, he awaits trial.
Duch, who ran the S-21 prison in Phnom Penh, told the court there were 196 such camps, now known as the Killing Fields, between 1975 and 1979. During those years, as many as two million people or a third of this country's population, perished under the Khmer Rouge government.
He said the camps were based on a prototype called M-13, built in 1971 in a communist-held zone when Pol Pot's forces battled the U.S.-backed Lon Nol government.
Duch's preferred weapons for torture were whips and electric shocks, he said, as they were simpler than waterboarding and less likely to kill the victim during questioning. Testimony in the trial resumes later this month.
Theary Seng, executive director of Cambodia's Center for Social Development, says Duch's testimony has gone a long way in telling ordinary Cambodians what happened under the ultra-Maoist Khmer Rouge.
"Even for us who have been following the tribunal since its establishment, who have been reading up on the tribunal, on the history of the Khmer Rouge, we have found surprising pieces of information we had not seen or read before," said Seng.
Duch also testified that Chinese diplomats and trade officials were in Cambodia at that time and were shielded from the killings going on behind the scenes.
The Khmer Rouge were ousted in 1979, after Vietnam invaded Cambodia, but many kept fighting in parts of the country into the 1990s. Pol Pot, the leader, went into hiding and was not found until 1997. But he died in 1998, before being brought to trial.
The Cambodian government and the United Nations negotiated for several years on setting up a human rights court to try other senior Khmer Rouge. The Duch trial is the first. But many of his colleagues have died, and the survivors are elderly, raising fears that very few Khmer Rouge leaders will be brought to justice.
Theary Seng says testimony like Duch's is cathartic for the country and is sparking debate among Cambodians who normally prefer not to talk about their tragic past.
"One of the most important aspects of the Duch trial has been hearing his words, his confessions, his explanations directly from himself…. So the Khmer Rouge tribunal is shedding light on this very, very dark period and it's helping to write history for Cambodians," said Seng.
And this, say human rights activists, should go a long way in helping to heal the survivors of the Killing Fields.