Cambodia's United Nations-backed war crimes tribunal says Ieng Sary, a former top official in the brutal Khmer Rouge movement, has died while on trial for genocide and war crimes.
The tribunal says the man known as Khmer Rouge "brother number three" died Thursday morning. He had been hospitalized since March 4. Court spokesperson Lars Olsen announced his death "with regret."
"We understand that many will be disappointed by the fact that we cannot conclude the proceedings against Ieng Sary and thereby we cannot make any determination on the guilt or innocence of the charges that have been brought against him."
The brother-in-law of Khmer Rouge leader Pol Pot, Ieng Sary was accused of orchestrating Cambodia's "killing fields" in the 1970s, leading to the deaths of up to two million people. He was a former foreign minister in the communist government.
At 87, he was the oldest of three senior Khmer Rouge leaders standing trial at the tribunal. His death increases the possibility the troubled tribunal may not be able to deliver verdicts against the aging leaders of the movement that oversaw the deaths of a quarter of Cambodia's population.
Khieu Samphan, the 81-year-old ex-president of the Khmer Rouge, and Nuon Chea, its 86-year-old former chief ideologue, all deny committing atrocities. Prison chief Kaing Guek Eav, known as Duch, is the only person to be found guilty and jailed by the tribunal.
Ieng Sary's wife, ex-social affairs minister Ieng Thirith, was also to face charges, but was ruled unfit to stand trial because of a degenerative mental illness. Pol Pot died in 1998.
Ieng Sary was one of the few public faces of the secretive Khmer Rouge leadership, serving as its top diplomat and in several other senior positions. He is accused of overseeing the slaughter of many of Cambodia's intellectuals.
After Vietnam toppled the Khmer Rouge in 1979, Ieng Sary was sentenced to death by a Vietnamese-backed war crimes tribunal. But he was pardoned by the late Cambodian King Sihanouk.
He defected to the government, along with thousands of fighters in 1996, in a move that would ultimately finish off the struggling Khmer Rouge, which by then had fled to a remote section of western Cambodia.
Ieng Sary and his wife were arrested at their luxury villa in Phnom Penh in 2007. He was put on trial by the Extraordinary Chambers in the Court of Cambodia in 2011, but the process against him has been slow and often delayed.
The court, which has spent more than $150 million since its formation in 2005, has been troubled by a lack funding and accusations of political interference by Cambodia's government, which has said further prosecutions could divide the country and spark a civil war.
Amnesty International said Ieng Sary's death underscores the need for the Khmer Rouge tribunal to expedite the genocide trials "without unnecessary delays." In a statement, it said the Cambodian government and other donor countries should provide the "full resources" required for the proceedings to continue, "so that justice may be served."