Ieng Sary, who co-founded the communist Khmer Rouge regime responsible for the deaths of an estimated 1.7 million Cambodians in the 1970s and decades later became one of its few leaders to be put on trial, has died at the age of 87.
The brother-in-law of late Khmer Rouge leader Pol Pot, Ieng Sary died before any verdict was reached in the trial, which began in late 2011 with four defendants and now has only two.
His death dashed hopes among survivors and prosecutors that he would be punished for his alleged crimes against humanity during the darkest chapter in his country's history.
Lars Olsen, a spokesman for the joint Cambodian-international tribunal where Ieng Sary had been on trial, confirmed his death. Chea Leang, a co-prosecutor for the tribunal, told the press that he died of "irreversible cardiac failure". Ieng Sary had suffered from high blood pressure and heart problems and was admitted to a Phnom Penh hospital on March 4 with weakness and severe fatigue.
His body will be taken by ambulance from the hospital to Malai in western Cambodia, a former Khmer Rouge stronghold where his family lives, for his funeral.
Ieng Sary was being tried along with two other former Khmer Rouge leaders, both in their 80s, and there are fears that they, too, could also die before justice is served. Ieng Sary's wife, former social affairs minister Ieng Thirith, had also been charged but was ruled unfit to stand trial last year because she suffered from a degenerative mental illness, probably Alzheimer's disease.
"We are disappointed that we could not complete the proceeding against Ieng Sary," Mr Olsen said, adding that the case against his colleagues, Nuon Chea, the Khmer Rouge's chief ideologist, and Khieu Samphan, an ex-head of state, will continue and will not be affected.
Ieng Sary founded the Khmer Rouge with leader Pol Pot. The Communist regime, which ruled Cambodia from 1975 to 1979, claimed it was building a pure socialist society by evicting people from cities to work in labour camps in the countryside. Its radical policies led to the deaths of an estimated 1.7 million people from starvation, disease, overwork and execution.
Ieng Sary was foreign minister in the regime and, as its top diplomat, became a much more recognisable figure internationally than his secretive colleagues.
The Khmer Rouge came to power through a civil war which toppled a US-backed regime. Ieng Sary then helped persuade hundreds of Cambodian intellectuals to return home from overseas, often to their deaths. The returnees were arrested and put in "re-education camps", and most were later executed, said Youk Chhang, director of the Documentation Centre of Cambodia, an independent group gathering evidence of the Khmer Rouge crimes for the tribunal.