Now old and infirm, four of the top surviving members of the Khmer Rouge's ruling elite are about to face justice, decades after their plans for a Communist utopia in Cambodia left an estimated 1.7 million people dead by execution, medical neglect, overwork and starvation.
On Monday a U.N.-backed tribunal, comprising Cambodian and foreign jurists, will begin trying them on charges including crimes against humanity, war crimes, genocide, religious persecution, homicide and torture. With Khmer Rouge leader Pol Pot long dead, this may be the nation's best chance to hold architects of the "Killing Fields" and the enslavement of millions of Cambodians accountable, though all four say they are innocent.
Nuon Chea, 84, was Pol Pot's No. 2 and the group's chief ideologist. Khieu Samphan, 79, was its former head of state. Ieng Sary, 85, was its foreign minister, and his 79-year-old wife, Ieng Thirith, was minister for social affairs.
Together, they form what the tribunal calls Case 002. The chief jailer of a notorious Khmer Rouge prison was convicted last year in the breakthrough Case 001. Political and financial pressures on the tribunal are raising doubts over whether there will ever be a Case 003.
Although this week's court sessions will be strictly procedural, with testimony and presentation of evidence expected to begin in August or September, it will mark the first joint appearance of the defendants in the dock, 32 years after the Khmer Rouge were kicked out of power in 1979 with the help of a Vietnamese invasion.
Pol Pot escaped justice with his death in 1998, then a prisoner of his own comrades as his once-mighty movement, in jungle retreat, was collapsing.
The tribunal, officially known as the Extraordinary Chambers in the Courts of Cambodia, started operations in 2006. Its first defendant was Kaing Guek Eav, also known as Duch, commandant of Tuol Sleng prison, known as S-21, where only a handful of prisoners survived. Up to 16,000 people were tortured under Duch's command and later taken away to be killed.
Duch, now 68, was sentenced to 35 years in prison for war crimes and crimes against humanity. His sentence was reduced to a 19-year term because of time previously served and other technicalities, bringing angry criticism from victims who called the punishment too lenient. Cambodia has no death penalty.
Alex Hinton, an anthropology professor at Rutgers University and author of a book about genocide in Cambodia, says Duch's case had "enormous symbolic value" because the prison was so closely associated with the horrors of the Khmer Rouge. But Case 002 "is more significant in that it will put the four most senior surviving Khmer Rouge leaders on trial for the first time."
"We will learn much about their thinking, the way their regime worked, and, ultimately, how their program of mass murder was enabled and unfolded," he says.
Despite the notoriety of the Khmer Rouge, proving the case may pose a challenge.
Duch expressed remorse, acknowledged responsibility for his actions and kept meticulous prison records that were mostly recovered when the Khmer Rouge fled Phnom Penh, the capital. The paper trial in Case 002 is less solid, and the defendants have not been as accommodating.
In previous public statements, they have tried to cast blame on others, such as the Vietnamese, who supposedly committed atrocities when they invaded, or Pol Pot himself, conveniently dead.
"Do I have remorse? No," said Ieng Sary in 1996, after he led a mass defection to the government. "I have no regrets because this was not my responsibility."
Ieng Sary, whose wife was the sister of Pol Pot's wife, blamed Khmer Rouge atrocities on the group's leader. He said he was a secondary figure who was excluded from Pol Pot's secret security committee, which decided policy and who would be executed.
The four defendants had lived freely before being taken into tribunal custody in 2007, often living in former Khmer Rouge strongholds. All are being held at a custom built jail in the same compound as the tribunal's headquarters and and courtroom.
This trial may be the tribunal's last, even though preliminary cases have been prepared against at least five more suspects. In recent months, it has been mired in controversy over what critics charge is an effort by the co-investigating judges _ from Cambodia and Germany _ to scuttle further prosecutions.
The process has always suffered from budgetary pressures, even though it will have spent almost $150 million from its start in 2006 until the end of this year.
More importantly, Cambodian Prime Minister Hun Sen, presumably wary that political allies who once served with the Khmer Rouge _ as he himself did_ could face prosecution, has declared he simply won't allow more trials.
While the Cambodian members of the tribunal's legal team have long been seen as susceptible to pressure from their government, co-investigating Judge Siegfried Blunk's agreeing to cut short investigations into Case 003 has raised hackles among human rights activists and other tribunal staff members, including some who appealed it to higher authorities and others who quietly resigned in protest.
"The current controversy in the court could lead to questioning by the public, which, added to the complexity and length of the procedures, may create fatigue and perhaps a kind of cynical reaction in front of what many people consider as an outside political interference," warns Kek Galabru of the Cambodian human rights organization Licadho. "Unfortunately, this could undermine the reputation of the court."
Andrew Cayley, the British co-prosecutor, says the process has taken a long time out of necessity.
"Justice has been delayed because the Khmer Rouge went on fighting the government until the late 1990s. It took 20 years to get a point where real trials could even be considered and then Cambodia needed help," he said.
"Its legal system was in ruins with few qualified lawyers left _ most had been murdered by the Khmer Rouge _ and yet they took the very courageous step of having these trials and addressing the past.
"That's hope. For all of us."
Associated Press writer Grant Peck in Bangkok contributed to this report.