A U.N.-certified tribunal sentenced two surviving Khmer Rouge leaders to life imprisonment for crimes against humanity.

On Thursday, Former Cambodia President Khieu Samphan, 83, and his "Brother Number Two" Nuon Chea, 88, were found guilty for the murder of 1.7 million to 2.2 million Cambodians during the "killing fields" revolutionary period from 1975 to 1979.

Like Us on Facebook

The government of Cambodia teamed up with the U.N. for the special tribunal that tried the two Khmer Rouge leaders.

Chief judge Nil Nonn said the pair were responsible for executions, murders and forced evacuations that marked the ultra-Maoist regime's years in power following the defeat of the Lon Nol regime. He termed their efforts a "joint criminal enterprise," resulting in the death of millions of people.

The trial began in 2011 and had been marked by controversy and delays. It took place just outside Phnom Penh in a specially constructed U.N.-designed modern facility that was a far cry from the primitive conditions that were celebrated during the Khmer Rouge revolution.

The phase one of the trial process focused on the forced evacuations of Cambodia's cities to the surrounding countryside. At the time, Khmer Rouge leaders sought to establish what they termed an agrarian utopia.

Trial evidence and procedural issues were so voluminous that two separate trials were instituted.

The second phase recently began with preliminary hearings on specific genocide charges. The trials have cost more than USD$200 million so far with the U.N. and private donors footing the bill.

While witnesses told horrific tales during the three years of trial, the fact was that these leaders were only the second and third senior leaders sentenced to punishment for Khmer Rouge crimes.

Commander of Phnom Penh's notorious S-21 prison Kaing Guek Eav, 71, who was called Duch, was sentenced four years ago to life in prison.

Other Khmer Rouge leaders escaped trial and punishment over the years. Leader Pol Pot perished in the jungles of northwest Cambodia in 1998 before the tribunal was established.

Foreign minister Ieng Sary died last year. His wife, Ieng Thirith, also a senior leader, was determined to be mentally incompetent and not eligible for trial.

Tagskhmer rouge, crimes against humanity, U.N, khmer rouge, Cambodia, killing fields, vietnam war