Ieng Thirith, a Khmer Rouge leader who was the highest-ranking woman in the genocidal regime that oversaw the death of nearly 2 million Cambodians in the late 1970s, has died. She was 83 years old.

Ieng Thirith was a sister-in-law of the movement's late supreme leader, Pol Pot. A Sorbonne-educated Shakespeare scholar, she served as minister of social affairs and was married to Ieng Sary, the regime's former foreign minister, who died in 2013 at age 87.

Her son, Ieng Vuth, said she had been suffering from dementia, heart troubles and other health problems.

Ieng Thirith was put on trial by a United Nations-backed tribunal seeking justice for crimes committed by the radical movement, but freed in September 2012 before its conclusion after being declared mentally unfit.