16,000 deaths, 19 years in jail – fury greets sentence for Pol Pot's executioner

It was 9.53am when the curtain in front of the glass-enclosed court chamber finally swept back. When it did, it revealed Kaing Guek Eav, once head of the Khmer Rouge's most notorious jail, sitting at a bench, his face expressionless, and dressed in a crisp blue shirt with grey trousers pulled up unnaturally high over a rounded stomach.

When he was escorted to his place in the dock a few moments later, the man better known as Comrade Duch looked tiny and unremarkable. Yet over the next 60 minutes, the chair of the court calmly and methodically outlined why this United Nations-backed tribunal had concluded that the slightly-built man with thinning grey hair was responsible for terrible, "heinous" offences that constituted crimes against humanity. Crucially, they confirmed that his claim to have been simply following orders constituted no defence whatsoever.

The court ruled that the obsessive, 67-year-old former maths teacher who had overseen and run the Tuol Sleng interrogation centre where around 16,000 people were beaten, tortured and questioned before being dispatched to die, should be sentenced to 35 years in jail. Yet, after taking into account time already served and other factors, the actual sentence was reduced to 18 years and 10 months.

If the authorities subsequently grant him parole, the man responsible for overseeing some of the 20th century's most vivid cruelty and violence – on a single day in June 1977, he authorised the execution of 160 children – could spend less than 13 years in jail.

When the court's decision was read out, Duch pressed his palms together in a traditional gesture of respect and bowed slightly towards the court's chairman before he was led from the room.

At the same time, many relatives of victims of the Khmer Rouge who had gathered to hear the sentence wept in relief. Yet their emotions rapidly turned to anger when the full implication of the court's decision was explained to them. While some had accepted it was likely the five-judge panel would grant Duch some reduction in sentence for his cooperation with the court and the admission of his role, few had anticipated the actual amount of time served would be so modest.

Outside the courthouse on the outskirts of Phnom Penh, 78-year-old Chum Mey, one of just a handful of people to have survived Tuol Seng, or S-21, where prisoners were subjected to beatings, electric shocks and water-boarding, repeatedly punched his fist into his palm in frustration.

"I am not happy at all. This is the second time for me that tears will drop. The first time was when I was tortured, and now [again] with this verdict," he declared, wiping his face. "Eighteen years is not enough. Duch gave orders to kill many people and I want him to be sentenced for his whole life."

A woman whose life had also been devastated by the Maoist-inspired regime, of which Duch was such a zealously dedicated member, could barely get out her words. "I can't accept this," said 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."

Theary Seng, a woman who lost both parents to the Khmer Rouge and who later wrote about her experiences in Daughter of the Killing Fields, said simply: "The sentence is a sham." She said the judgment would dilute the energy to proceed with the prosecution of four other Khmer Rouge officials, all of them more senior than Duch.

Rob Hamill, the brother of New Zealander Kerry Hamill, one of a handful of Westerners killed by the Khmer Rouge, told reporters: "All I can say is my family... would not want to see this man set free, even if it's in 19 years' time. It's reality but I'm not happy."

Prosecutors have 30 days to decide whether they will challenge the court's ruling and Cambodian co-prosecutor Chea Leang said the team would study the judgment. "Nothing can erase the pain and suffering endured by the Cambodian people," she said. "However, today's judgment finally represents credible legal acknowledgement of the Khmer Rouge's criminal policies."

British lawyer Andrew Cayley, her co-prosecutor at the $100m (£65m) tribunal, which took 10 years to arrange, said he believed that by the standards of such international tribunals the sentence had been considerable. He also said he believed it very unlikely that Duch would become eligible for parole.

In the days leading up to the sentence, representatives of the regime's victims had urged the court to impose a sentence of nothing less than 40 years.

There was much talk of a punishment that was "equitable".

At the same time, they recognised the impossibility of such a thing; as one international analyst said, the court could have ruled that Duch be "chopped into 16,000 pieces" and yet it would not bring back one of his victims.

Some observers have claimed the Cambodian people have been uninterested in the proceedings of the trial, which heard 77 days worth of evidence and testimony. While there were no public celebrations last night in Phnom Penh, ordinary Cambodians – especially those aged above 45 – were very much aware of the day's significance.

More than 1,000 people from rural parts of the country had taken up the court's offer of taking a bus to the capital to attend the sentencing.

At a flower market close to the national museum, a man called Khiv Phalna perhaps summed up the enduring pain of so many Cambodians.

In the absence of the death penalty, he said, 19 years was a suitable enough punishment. His voice trembled as he recalled the four relatives he said he had lost to the regime, which killed up to 1.7 million people as it ravaged the nation between 1975 and 1979.

"This somehow can help reduce the anger," he said, sitting amid bunches of heavily scented roses and lotus flowers. "He will now be in a cell. It's better than if we had not had a trial."

Survivor's story: 'I want him to do forced labour, like those sent to Tuol Sleng'

The last day Norng Chan Phal saw his mother, he was nine years old and she was staring down at him from a second-floor cell in Tuol Sleng jail. Tears streaked her face as she gazed at him and his six-year-old brother, and then she was gone. A week or so later, Vietnamese troops drove into Phnom Penh, found the notorious S-21 prison and discovered the young boy and his brother hiding beneath a pile of discarded prisoners' clothes. There was no sign of his mother.

"Before we were separated in Tuol Sleng, my mother gave me a box of balm," Mr Norng, now 41, recalled this week as he sat at a café close to the jail, his daughter sipping a cold drink. "My mother had wanted me to carrying on looking after my brother, but there was hardly any left."

He added: "I remember her looking down to me from the window. Her hands were on the bars and tears ran down her face. I remember her clearly."

Along with his brother, Mr Norng, who works as a part-time driver of heavy machinery, is one of the youngest known survivors of the notorious jail overseen by Duch. Recently discovered images show the two young boys in the company of Vietnamese soldiers, looking emaciated and terrified. There was no food, said Mr Norng, and they were constantly bitten by mosquitoes. They had hidden beneath the clothes, he said, in the hope their mother would come and find them.

Like all survivors, Mr Norng is forced to accept he is one of Cambodia's lucky ones. And yet every day he struggles with what he experienced after first his father, and then his mother, were arrested by the Khmer Rouge and taken to S-21. Last year, when giving evidence to the court, he broke when he talked about his mother. He gathered the courage, however, to challenge Duch when he claimed no children had been held at the jail. Duch was forced to backtrack.

Mr Norng, who spent a year following Vietnamese troops before spending the subsequent 10 years in an orphanage, said ahead of the tribunal that he was hoping "the souls of my parents" would be released by the deliverance of a suitable sentence. Last night his phone had been switched off.

Before he and his daughter got up to leave, slipping into the light morning traffic on his motor-scooter, Mr Norng had said: "I want Duch to be in jail for life. I want him to do forced labour, like the prisoners in Tuol Sleng. He should be blindfolded and his hands tied behind his back. He should not wear a shirt and then someone should lead him around Tuol Sleng. He should apologise to the bones."