khmer rouge
Former foreign minister Ieng Sary and his wife and ex-social affairs minister Ieng ThirithGetty

The former "first lady" of Cambodia's genocidal Khmer Rouge regime died onSaturday, 22 August, without her victims being able to see her face trial. Ieng Thirith, 83, a French-educated revolutionary, was one of the few women in the senior leadership of the movement behind the horrors of the "Killing Fields" era.

Under the totalitarian dictatorship urban dwellers were forced to moved to the countryside to work in collective farms. Led by "Brother Number One" Pol Pot (who died in 1998), from 1975-1979 the regime murdered between one to three million Cambodians by starvation, overwork and execution, from a total population of just over eight million.

Thirith was one of four suspects charged by the Extraordinary Chambers in the Courts of Cambodia (ECCC) – the country's UN-backed war crimes tribunal – but was freed in 2012. The case against her was suspended following a ruling she was unfit to stand trial due to dementia.

Thirith used family connections to reach the upper echelons of power. She was Pol Pot's sister-in-law and served as the regime's social affairs minister; her husband Ieng Sary was foreign minister. Sary died in 2013 at 87 years of age while on trial before the ECCC for war crimes and genocide.

The remaining two defendants were sentenced to life imprisonment after being found guilty of crimes against humanity by the ECCC. They were Khieu Samphan, the 83-year-old former head of state, and Nuon Chea, 88, Pol Pot's deputy. The two are currently being tried on further charges of genocide.

As well as mass murder, extreme torture was routine under the regime. Earlier this year the ECCC heard testimony that detainees had acid poured into open wounds and were disembowelled. Some had internal organs removed and eaten.

Earlier this year Thirith was admitted to hospital in Thailand with heart, bladder and lung problems. She died in Thailand's Pailin province, a former Khmer Rouge stronghold near the Cambodian border where many Khmer leaders settled after they were defeated by the Vietnamese. Her son Ieng Vuth is the province's deputy governor.

"The accused passed away at approximately 10.30am on August 22 in Pailin, Cambodia," said the ECCC in a statement. "She was released under a regime of judicial supervision. She remained under judicial supervision until her death."