Nuon Chea
Nuon Chea joined the Communist Party of Kampuchea (the Khmer Rouge's official name) while studying law at Thammasat University in Bangkok. In 1960, he was appointed Deputy Secretary to oversee the security of the party and the state. His charges included Phnom Penh's S-21—the notorious interrogation and torture center. It is estimated that Nuon Chea is responsible for the death of 1.7 million people during the rule of the Khmer Rouge.