When the ornately decorated court complex on the outskirts of Phnom Penh opened its doors in the summer of 2007 it was seen as a milestone in Cambodia's tortured journey towards justice.
Survivors of the Khmer Rouge regime, which killed up to 1.7 million of its own citizens, flocked to see the first defendant, a slight, wiry prison commander called Kaing Guek Eav, brought before the judges.
"I want to confront him, to ask who gave him the orders to kill the Cambodian people, said Chum Mey, one of just a handful of survivors from the Tuol Sleng jail, from which Kaing Guek Eav - also known as Comrade Duch - dispatched up to 14,000 people to the killing fields.
Yet six years on, the tribunal is confronting little short of a crisis. In the latest of a series of setbacks, one of three elderly defendants standing trial for war crimes has died in hospital. Some of the same people who celebrated when the tribunal began now say it has become a sham and should be halted.
Survivors of the Maoist-inspired regime said the death yesterday of Ieng Sary, 87, who served as the regime's foreign minister, highlighted a complaint they had repeatedly made - namely that the slow pace of the trial is undermining justice.
"I'm very disappointed that Ieng Sary escaped justice, escaped the trial," said Ou Virak, whose father was killed by the regime and who now heads the Cambodian Human Rights Centre. "This is exactly what we have been saying. There is no time to waste."
Theary Seng, whose parents were also killed and who spent time as a child in forced labour camps, said it was not surprising young Cambodians were taking to social media to call for the UN-backed tribunal to be halted. She said the UN should invoke its legal right to end the trial.
"This tribunal is a war of attrition," said Ms Seng, who wrote about her experiences in a memoir, Daughter of the Killing Fields. "The death of Ieng Sary is another example of how we, the victims, are losing???"
The death of the man who was among the regime's most recognisable faces leaves only two senior members now on trial - Nuon Chea, the regime's ideologist and right-hand man of its leader Pol Pot, and the former president, Khieu Samphan.
As it is, a team of doctors is due to check the medical condition of 86-year-old Nuon Chea next week, to determine whether he is well enough to continue being tried. In 2011, the court decided that Ieng Thirith, the only female leader to be charged, was unfit to continue with the proceedings after she was found to be suffering from dementia.
The tribunal has been rocked by difficulties since it began. The most significant challenge has been political interference from the government of Hun Sen, Cambodia's Prime Minister and himself a former officer with the Khmer Rouge.
His influence has resulted, in effect, in a block on expanding the number of suspects to be tried. Experts had suggested there was sufficient evidence to bring several other former Khmer Rouge leaders before the tribunal, but the moves were opposed by Cambodian authorities.
Such was the scale of interference that, in October 2011, one of the investigating judges, Siegfried Blunk, quit his post in frustration. The interference has also slowed proceedings.
The unwillingness of the Cambodian authorities to engage with the tribunal has also been exposed in other ways. In recent weeks, the trial's proceedings ground to a halt after local staff went on strike, complaining that they had not been paid for months. Hun Sen is responsible for paying the salaries of Cambodian staff.
Activists had insisted that however painful the tribunal might be it was an unavoidable undertaking if Cambodia wished to move forward from its dark, recent past. Perhaps a quarter of Cambodia's population was murdered or else starved to death between April 1975 and January 1979, when they were forced from the cities and made to work on farms.
The tribunal has also raised uncomfortable questions for many of the world's leading nations, some of which are funding the £115m project. China openly supported the regime, while a number of countries, including the UK, allowed the Khmer Rouge to retain Cambodia's seat at the UN General Assembly after they were ousted from power by Vietnamese troops.
The tribunal has also drawn attention to the brutalising effect of the massive secret bombing campaign of the US in Cambodia and Laos, directed against Khmer Rouge and South Vietnamese forces and which some historians have argued created the circumstances for the Khmer Rouge to seize power.
Yet the achievements of the tribunal have so far been modest. Only Comrade Duch has been convicted. He was found guilty of war crimes in 2010 and sentenced to 19 years in jail.
The frustrations now being voiced among ordinary Cambodians may have reached unprecedented levels. Darathtey Din, an international relations student, saw the news about Ieng Sary's death on her Facebook feed, and quickly typed out her thoughts.
"I say, put an end to the tribunal to save money for development in other fields because it seems like the former Khmer Rouge leaders die because of old age, one by one before any verdict can be made," she wrote.
Another student, 23-year-old Suon Sopheaktra, wrote that it was essential that the court redoubled its efforts before the public lost all hope.
"We would all regret if the huge amount of money the international donors have poured into this court is in vain, especially when the court has been delayed time and again with the threats from a very powerful person," he wrote.
Yesterday, Lars Olsen, a spokesman for the Extraordinary Chambers in the Court of Cambodia, said Mr Ienghad died in the Khmer Soviet Friendship Hospital in Phnom Penh, where he had been admitted on 4 March. "He has been suffering from intestinal problems," said Mr Olsen. "He has been hospitalised several times during the last year."
Mr Ieng's body was being taken to Malai in western Cambodia, a former Khmer Rouge stronghold where his family lives, for his funeral.
When Mr Ieng was arrested in 2007, he refused to co-operate with the court, insisting that he had been pardoned by King Norodom Sihanouk. The tribunal ruled that the pardon did not cover its indictment against him and that he had to stand trial. On Wednesday, the court issued a statement formally announcing that proceedings against him had been discontinued.
ON TRIAL: FIGURES OF FEAR
Joined the Khmer Rouge in the late 1960s, became Head of State for Democratic Kampuchea in 1976 and succeeded the leader, Pol Pot in 1987. Samphan was arrested in 2007, and is on trial for crimes against humanity and genocide. The 81-year-old, who has suffered a stroke, denies the charges.
Known as Brother Number Two, Nuon Chea was Pol Pot's deputy and chief ideologist. Like Samphan, he is accused of crimes against humanity and genocide between 1975 and 1979. Now 86, he too is in frail health and denies the charges.