(CNN) -- Cambodia's war crimes court Friday rejected the appeal a man who ran a Khmer Rouge regime torture prison and instead increased the man's sentence to life imprisonment.
Kaing Guek Eav, commonly known by his alias, Duch, was appealing his 2010 conviction and 35-year sentence arguing that he was just following orders of senior leaders of the Khmer Rouge regime.
Duch was 67 at the time of his convictions, which was for war crimes, crimes against humanity, murder and torture. He was was the head of the S-21 prison where about 14,000 people died. Few people taken to the prison made it out alive; only about a dozen were found by the Vietnamese, who invaded Cambodia in 1979.
The judge, in announcing Duch's sentence in 2010 saiid he took into consideration that the defendant had expressed remorse, admitted responsibility and cooperated with the court. The judge also took into account the "coercive environment" of the Khmer Rouge, he said.
Duch pleaded guilty and asked for forgiveness. In the trial, he argued that international law did not apply to him because he was just following orders.
The tribunal began its work in 2007 after a decade of on-and-off negotiations between the United Nations and Cambodia over the structure and functioning of the court. The 2010 verdict was the court's first.
At least 1.7 million people -- nearly a quarter of Cambodia's population -- died under the 1975-1979 Khmer Rouge regime from execution, disease, starvation and overwork, according to the Documentation Center of Cambodia.