Kaing Guek Eav, a former jailer for Cambodia's Khmer Rouge suspected of overseeing the deaths of some 15,000 people, was sentenced by Cambodia's UN-backed court to spend the rest of his life in jail.
Kiang Guek Eav was originally sentenced to 30 years in jail for war crimes and crimes against humanity but judges ruled on appeal that the sentence "did not reflect the gravity of the crimes."
"The crimes by Kaing Guek Eav were undoubtedly among the worst in recorded human history," the president of the Supreme Court Chamber Kong Srim said. "They deserve the highest penalty available."
Between 1975 and 1979 the Khmer Rouge were responsible for killing an estimated 2 million people.
Kiang Guek Eav was the head of the S-21 prison, the main prison under the Khmer Rouge.
Compiled from agency reports