Mr. Ieng was moved from his tribunal holding cell to a Phnom Penh hospital March 4 after suffering from weakness, fatigue and gastrointestinal problems, according to his attorneys. The cause of death was unknown, although Mr. Ieng was also being treated for heart problems and high blood pressure.
Lars Olsen, spokesman for the U.N.-backed Extraordinary Chambers in the Courts of Cambodia, confirmed Mr. Ieng’s death but said it will not affect the court proceedings for his co-defendants, chief ideologist Nuon Chea and ex-head of state Khieu Samphan.
The only person convicted in connection with Khmer Rouge atrocities is former prison chief Kaing Guek Eav, known as Duch, who was sentenced in February 2012 to life in prison for overseeing the killings of more than 12,000 prisoners. Pol Pot died in Thailand in 1998 without answering to an international tribunal.
In the Khmer Rouge regime, Mr. Ieng was known as “Brother No. 3,” in a position of authority only exceeded by Pol Pot and Nuon Chea.
Mr. Ieng had been a founder of the Khmer Rouge in the 1960s. The Communist-inspired insurgent movement drew a following against the backdrop of the Vietnam War, the U.S. bombing of Cambodia, the militarist coup led by Western-backed Cambodian Gen. Lon Nol and an erupting civil war.
Once in Phnom Penh, the Khmer Rouge quickly began to purge the political opposition and assert a radical vision of social engineering. Execution, starvation and forced labor were the tools used to terrify the population. The horrors were most vividly expressed to a world audience through the Hollywood movie “The Killing Fields” (1984).
As deputy prime minister of foreign affairs, Mr. Ieng served as the Khmer Rouge’s public face abroad. To the international community, Mr. Ieng could be a gracious diplomat — in October 1977, he hosted a cocktail party in New York for 200 diplomats to showcase a film “extolling the glories of brave new Kampuchea,” according to Time magazine.
But at home, he allegedly played a far darker role. Mr. Ieng financed the return of Cambodian expatriates with the claim that they could help the fledgling government succeed. When they arrived in Democratic Kampuchea, as Cambodia was then renamed, these diplomats and intellectuals were sent by the thousands to “re-education camps” for forced labor. More than 90 percent were executed, according to Mr. Ieng’s entry in “A Biographical Encyclopedia of Contemporary Genocide.”
The Khmer Rouge government completely destabilized Southeast Asia in the years after the Vietnam War, provoking the Vietnamese to invade in January 1979 and occupy the country for much of the 1980s. In that period, Mr. Ieng fled to Thailand and, along with Pol Pot, was found guilty in absentia by a Cambodian show trial and sentenced to death.