Ieng Sary was one of the Khmer Rouge's most powerful leaders: he was ranked number three in the hierarchy and was the brother-in-law of the movement's leader Pol Pot.

For more than a decade spanning the 1970s, Ieng Sary was also the public face of one of the 20th century's most secretive and brutal regimes, which oversaw the death of two million Cambodians from execution, disease, starvation and overwork.

All of that was carried out in the crucible of a revolution that would upend Cambodian society and remake it in the model of a peasant paradise. It failed utterly, and the country and its people still bear the scars.

Revolutionary

Ieng Sary was born in neighbouring Vietnam in 1925, but came to Cambodia for his schooling. By all accounts he did well academically; he also found left-wing politics appealing. By the time he was 25 he was at university in Paris, one of a number of Cambodians whose education benefited from the largesse of the former colonial power France.

In Paris, he and other men and women who went on to lead the Cambodian Communists became influenced by the unyielding vision of Stalinism, the preferred diet of the French Communist Party. He returned to Cambodia in 1957 and, along with Pol Pot and a small group of like-minded leftists, plotted revolution.

It took years, but finally, in April 1975, the Khmer Rouge - as they were by then known - captured Phnom Penh, and Cambodia entered its darkest years. The cities and towns were forcibly evacuated, and millions were forced to labour for years under threat of death in vast work camps planting rice or building irrigation systems. Those who fell foul of the regime were summarily executed. Hardly a family was left unscathed.

Exodus

It was not to last. Less than four years after taking power, this brutal movement was driven from Phnom Penh by a combined force of Vietnamese soldiers and Khmer Rouge defectors. The Khmer Rouge fled west to the Thai border, where an international coalition - Thailand, the United States and China, among others - who were united in their dislike of Hanoi kept them in guns and food to fight the Vietnamese-backed government in Phnom Penh.

Yet the friends of the Khmer Rouge eventually tired of supporting them. In the late 1990s, the movement collapsed in a final round of internecine bloodshed. Pol Pot died in 1998.

By then, Ieng Sary had defected to the government in Phnom Penh. When he did so, he brought with him thousands of fighters and an amnesty from prosecution.

However, the UN-backed tribunal later ruled his amnesty invalid and Ieng Sary was arrested in 2007 and brought to the detention centre on the outskirts of Phnom Penh. Other than brief trips to hospital, this was where he spent the last years of his life on trial for genocide, war crimes and crimes against humanity - all of which he denied.

He was joined in detention by his wife, Ieng Thirith, who had been the social affairs minister; Nuon Chea, who was the chief ideologue of the Khmer Rouge and is known as Brother Number Two; and Khieu Samphan, the former head of state.

The four of them comprised the senior leaders, whose trial is known as Case 002 and which is the centrepiece prosecution of the UN-backed war crimes court. However, in 2012, the court released Ieng Thirith, ruling that her dementia had made her unfit for trial. The death of her husband leaves just Nuon Chea and Khieu Samphan in the dock.

Death

Ieng Sary was widely felt to be the most frail of the four defendants. He was also the eldest. Despite Ieng Sary's worsening health in recent years, said his international defence lawyer Michael Karnavas, his death was a surprise.

"At the end, he could not digest food, so that was the problem. That placed a lot of stress on his heart which was already weak," said Karnavas. "In the last ten days his health deteriorated rather rapidly. [But] nobody expected this - at least not this soon."

Ieng Sary's body was released to his family later on Thursday, March 14, and will be taken to Malai, a former Khmer Rouge stronghold in the far west of Cambodia. There he will be cremated in accordance with the country's predominant Buddhist religion.

Fallout

Tribunal spokesman Lars Olsen said Ieng Sary's death would make little difference to the proceedings in Case 002.

"Case 002 is not over," Olsen told a press conference on Thursday at the hospital, just minutes after Ieng Sary's body had been taken away. "The charges against Nuon Chea and Khieu Samphan … are not affected by the passing of Ieng Sary. The [tribunal] will continue its proceedings against Nuon Chea and Khieu Samphan."

Yet others said Ieng Sary's death must act as a wake-up call to a tribunal that has grown increasingly dysfunctional.

Youk Chhang, the head of Documentation Center of Cambodia (DC-Cam), the genocide and research organization in Phnom Penh that focuses on the crimes of the Khmer Rouge, said those involved seem to have lost sight of the core fact at the heart of this judicial process: that the victims of the Khmer Rouge deserve justice.

Youk Chhang says Ieng Sary's death must refocus the attention of the government, the UN and donors. The tribunal has not conducted any hearings this month due to a strike over unpaid wages. Besides the funding issue, which has long been a problem, the court has also been damaged by longstanding allegations of corruption and political interference.

"The government and the UN have the obligation - they made the promise after the Holocaust over 60 years ago - to punish and prevent genocide," he said. "They need to work out their differences to allow the court to complete [its work]."