Nearly 40 years after suffering the totalitarian nightmare of the Khmer Rouge, victims of Cambodia’s horrific history were granted a small measure of justice on Friday. An international criminal tribunal convicted two aging former Khmer Rouge leaders in a historic ruling that for the first time legally defines the regime’s crimes as genocide.

The defendants, Nuon Chea, 92, and Khieu Samphan, 87, are among the last surviving chieftains of the Khmer Rouge, a brutal regime that decimated Cambodia from 1975-1979 in an effort to recreate a utopian agrarian society. An estimated 1.7 million people—or more than 20% of the population—died. Many succumbed to starvation, while others were tortured to death in camps and killing fields across the small Southeast Asian country.

The U.N.-back court, informally known as the Khmer Rouge Tribunal, handed both Nuon Chea and Khieu Samphan life in prison on Friday, terms which duplicate their 2014 convictions for the forced evacuation of Phnom Penh, Cambodia’s capital.