More than three decades after the brutal Khmer Rouge regime ended, a U.N.-backed war crimes tribunal on Thursday found the regime's two most senior surviving leaders guilty of crimes against humanity and sentenced them to life in prison.

Nuon Chea, 88, and Khieu Samphan, 83, were found guilty of "extermination encompassing murder, political persecution, and other inhumane acts comprising forced transfer, enforced disappearances and attacks against human dignity," chief judge Nil Nonn told the hearing. According to the defendants' lawyers, both will file appeals to their verdicts. 

Khieu Samphan in 2008. (REUTERS/Chor Sokunthea)

The deadly rule of Khmer Rouge terrorized the civilian population of Cambodia during the 1970s, leaving more than 1.7 million people dead—about a quarter of the population at the time. The regime, led by Pol Pot, attempted to enforce an agrarian Communist utopia, in which all citizens worked in fields and urban communities ceased to exist. With this goal, the leaders of the regime set out to destroy cities and intellectuals; for example, if a citizen wore glasses or could read, the followers of Khmer Rouge would mark him or her a counterrevolutionary and use torture or death as punishment. Scores of the population died from starvation, exhaustion, and disease after being forced out of their homes in what became one of the worst genocides of the 20th century.

The judgments, therefore, made it "a historic day for both the Cambodian people and the court," tribunal spokesman Lars Olsen said. "The victims have waited 35 years for legal accountability, and now that the tribunal has rendered a judgment, it is a clear milestone."

Even so, many victims of the regime felt the day has come 35 years too late.

Nuon Chea in 2008. (REUTERS/Chor Sokunthea)

"We wonder why they took so long," Dara Duong, whose father, grandparents, uncle, and aunt were murdered by the Khmer Rouge when he was four years old, told TIME. "We are not satisfied with this process."

In fact, the process had been, as The New York Times put it, "tortuous" for victims to handle:

To watch the court proceedings, to hear the lawyers' objections, to sit through the delays and the quibbles and the endless parsing of words, it's enough to make a good number of Cambodians want to simply unshackle the prisoners and set them free. Game over. 

And at this point, it seems unlikely any more Khmer Rouge leaders will stand trial. Pol Pot died in 1998 while on the run, and five other defendants have not been officially named. Delays upon delays have only hampered judgments. 

Still, justice has been served, offering a glimmer of closure for some who have watched two frail, arrogant men enjoy generations free of guilt.

"There's a satisfaction knowing that these people will never be released," Youk Chhang, a survivor who had been forced to leave the city of Phnom Penh in 1975, told The New York Times. "They lost their freedom."