PHNOM PENH, Cambodia -- Ieng Sary, who co-founded Cambodia's brutal Khmer Rouge movement in 1970s, served as its public face abroad and decades later became one of its few leaders to face justice for the deaths of well over a million people, died Thursday. He was 87.His death came during the course of his trial with two other former Khmer Rouge leaders by a joint Cambodian-international tribunal. He had been in declining health before tribunal spokesman Lars Olsen confirmed he died Thursday morning.Ieng Sary founded the Khmer Rouge with Pol Pot, his brother-in-law. 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 labor camps. Its 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 recognizable figure internationally than his secretive colleagues. In 1996, years after the overthrown Khmer Rouge retreated to the jungle, he became the first member of its inner circle to defect, bringing thousands of foot soldiers with him and hastening the movement's final disintegration.The move secured him a limited amnesty, temporary credibility as a peacemaker and years of comfortable living in Cambodia, but that vanished as the U.N.-backed tribunal built its case against him.The Khmer Rogue came to power through a civil war that toppled a U.S.-backed regime. Ieng Sary then helped persuade hundreds of Cambodian intellectuals to return home from overseas, often to their deaths.Ieng Sary was arrested in 2007, and was tried with Nuon Chea, the Khmer Rouge's chief ideologist, and Khieu Samphan, an ex-head of state, in monthslong proceedings that began in late 2011 on charges including crimes against humanity, war crimes and genocide.Only one other former Khmer Rouge official has been tried: ex-prison chief Kaing Guek Eav, who was sentenced to life in prison.