PHNOM PENH, Cambodia – A war crimes tribunal sentenced the Khmer Rouge’s chief jailer Monday to a prison term that will see him serve less than half a day for every person killed at the notorious torture center he commanded.

Survivors expressed anger and disbelief that a key player in the genocide that wiped out a quarter of Cambodia’s population could one day walk free — despite being convicted of war crimes and crimes against humanity.

“I can’t accept this,” sobbed Saodi Ouch, 46, shaking so hard she could hardly talk. “My family died … my older sister, my older brother. I’m the only one left.”

Kaing Guek Eav, known as Duch, was the first major Khmer Rouge figure to face trial more than three decades after the “killing fields” regime tried to turn the country into a vast agrarian society — leading to the deaths of 1.7 million people.

As commander of the top secret Tuol Sleng prison — code-named S-21 — the 67-year-old Duch admitted to overseeing the torture and deaths of as many as 16,000 people.

He was sentenced to 35 years in prison, but will spend only 19 years in jail – 11 years were shaved off for time served and another five for illegal detention in a military prison.

“It is just unacceptable to have a man who killed thousands of people serving just 19 years,” said Theary Seng, a human rights lawyer, who lost both her parents to the Khmer Rouge and has been working with other victims to find justice.

“It comes down to serving 11½ hours per life that he took,” she said, adding that if prosecutors could get only such a lenient sentence in a case where the defendant admitted his guilt, they could expect even less in the upcoming trial of four senior Khmer Rouge figures.

The U.N.-backed tribunal is scheduled to try the group’s top ideologist, 84-year-old Nuon Chea, its former head of state, Khieu Samphan, 79, and two other top leaders, both in their 80s, early next year. Unlike Duch, they have denied any guilt.

Several other major figures have died, including the Khmer Rouge leader, Pol Pot, in 1998.

Judges said that in handing down their verdict Monday, they took into consideration the historical context of the atrocities: The 1975-79 regime was the product of the Cold War times.

They also recognized that Duch — unlike any of the others in detention — was not in the Khmer Rouge’s inner circle, had cooperated with the court and shown expressions of remorse, however “limited.”

But they flatly rejected claims that he was acting on orders from the top or that he was a “cog in the machine” who could not get out.

They said he signed off on all executions and was often present when interrogators used torture to extract confessions, including pulling out prisoners’ toenails, administering electric shocks, and waterboarding. Sometimes he even took part.

Duch revealed little emotion throughout the 77-day trial. As the court handed down its sentence Monday, he stood rigidly and looked into the distance, his eyes occasionally shifting from side to side without making any contact.

“He tricked everybody,” said Chum Mey, 79, one of just a few people sent to Tuol Sleng prison who survived. The key witness wiped his eyes. “See … my tears drop down again. I feel like I was victim during the Khmer Rouge, and now I’m a victim once again.”

Like many key players in the Khmer Rouge, Duch was an academic before he became a revolutionary. The former math teacher joined Pol Pot’s movement in 1967, three years before the United States started carpet-bombing Cambodia to try to wipe out Northern Vietnamese troops and Viet Cong inside the border. 1976, he was the trusted head of its ultimate killing machine, S-21.

After a Vietnamese invasion forced the Khmer Rouge from power in 1979, Duch fled, leaving behind thousands of documents and negatives at Tuol Sleng, once a secondary school.