In a historic first, a UN-backed court on Monday sentenced a former Khmer Rouge prison chief to 30 years in jail for the executions of about 15,000 people during Cambodia's "Killing Fields" era.
Kaing Guek Eav, better known as Duch, is the first Khmer Rouge cadre to face justice in an international tribunal over the deaths of up to two million people through starvation, overwork and execution under the 1975-1979 regime.
The maths teacher-turned-revolutionary was convicted of charges including crimes against humanity and war crimes.
But to the dismay of survivors and relatives of victims, the court took into account the years he has already served since his arrest in 1999, meaning that the 67-year-old could live to see freedom in 19 years' time.
After apologising during his trial in Phnom Penh for overseeing mass murder of men, women and children at Tuol Sleng prison - also known as S-21 - Duch shocked the court in November by finally asking to be acquitted.
"The role of the accused as the undisputed head of S-21 is confirmed by the accused's own admission, the testimony of witnesses and civil parties," head judge Nil Nonn said as he read out the verdict.
"Every individual detained within S-21 was destined for execution in accordance with the Communist Party of Kampuchea policy to smash all enemies," he added.
But the court found there was insufficient evidence to prove Duch personally committed torture or other inhumane acts, the judge said.
Tuol Sleng was the centre of the Khmer Rouge security apparatus and thousands of inmates were taken from there for execution in a nearby orchard that served as a "Killing Field".
The court found Duch "worked tirelessly to ensure that S-21 ran as efficiently as possible and did so out of unquestioning loyalty to his superiors".
Crowds of Cambodians, including regime survivors and Buddhist monks, turned up at the specially built court on the outskirts of Phnom Penh, hoping finally to see justice for the Khmer Rouge's crimes.
Duch was initially given 35 years but the court reduced the jail sentence after ruling that he had been detained illegally for years by a Cambodian military court before the UN-backed tribunal was established.
Prosecutors, who had asked for a 40-year prison term, hailed the judgement as a historic day for Cambodia, although they said they would consider appealing for a stiffer sentence.
"This is a court case, not a football match, so there are no winners or losers. It's really a question of whether justice has been applied," deputy prosecutor Bill Smith told reporters.
Duch, wearing a blue shirt, slumped in his chair as the tribunal read out the verdict in a courtroom shielded by a huge bullet-proof screen to prevent revenge attacks by Khmer Rouge victims.
Led by "Brother Number One" Pol Pot, the Khmer Rouge was responsible for one of the worst horrors of the 20th century, wiping out nearly a quarter of Cambodia's population.
Rising to power as a tragic spin-off of the US war in Vietnam, the communist movement emptied Cambodia's cities to take society back to a rural "Year Zero", purging city dwellers, intellectuals and even people who wore glasses.
The Khmer Rouge was ousted by Vietnamese-backed forces in 1979, but continued to fight a civil war until 1998. Pol Pot died in the same year.
Duch has been detained since 1999, when he was found working as a Christian aid worker in the jungle, and was formally arrested by the tribunal in July 2007.
The court has faced controversy over allegations of interference by the government and claims that Cambodian staff paid kickbacks for their jobs.
The joint trial of four more senior Khmer Rouge leaders charged with genocide is expected to start in 2011.
The court is also investigating whether to open more cases against five other former Khmer Rouge cadres after a dispute between the international and Cambodian co-prosecutors over whether to pursue more suspects.