A United Nations-backed court on Friday found two leaders of Cambodia’s brutal Khmer Rouge regime guilty of committing genocide between 1975 and 1979, and sentenced to life in prison, BBC reported. While 92-year-old Nuon Chea was the deputy of regime leader Pol Pot, Khieu Samphan, 87, was the head of state.

Nearly 2.2 million people – most of them ethnic Khmer people – died of starvation, torture or disease in labour camps or were bludgeoned to death during mass executions, Reuters reported. By the time the regime was overthrown in 1979, about 25% of Cambodia’s population had died.

Nuon Chea was found guilty of genocide for attempting to wipe out Cham Muslims and ethnic Vietnamese Cambodians, while Khieu Samphan was found guilty of genocide against ethnic Vietnamese, and of various crimes against humanity. The two leaders have denied the charges.

Chea and Samphan are already serving life sentences for their convictions in 2014 for crimes against humanity.

“The chamber finds that prisoners were brought to interrogation rooms, handcuffed and blindfolded, their legs chained during questioning,” the Extraordinary Chambers in the Courts of Cambodia said in its verdict, The Guardian reported. The court added that the interrogation methods included beating prisoners with sticks, whips, electric shocks and suffocation, and the extraction of toenails and fingernails.

The Khmer Rouge was a radical Maoist movement that tortured and killed several former government officials, intellectuals, minorities, and their families in the four years it was in power. Pol Pot remained on the run till 1997 and died under house arrest in 1998.

The Extraordinary Chambers in the Courts of Cambodia, established in 2006, has so far only convicted three people for the regime’s atrocities.