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 more than a million people, died Thursday morning. 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. Lars Olsen, a spokesman for the tribunal, confirmed his death.

Ieng Sary founded the Khmer Rouge with leader 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 in the countryside. Its radical policies led to the deaths of an estimated 1.7 million people from starvation, disease, overwork and execution.