Son Sen ( ; 12 June 1930 – 15 June 1997), alias Comrade Khieu () or "Brother Number 89", was a Cambodian Communist politician and soldier. A member of the Central Committee of the Communist Party of Kampuchea/Party of Democratic Kampuchea, the Khmer Rouge, from 1974 to 1992, Sen oversaw the Party's security apparatus, including the Santebal secret police and the notorious security prison S-21 at Tuol Sleng. Son Sen was responsible for ordering the massacre of more than 100,000 people in the Eastern Zone of Cambodia during the last six months of 1978. Sen was married to Yun Yat, who became the Party's minister of education and information. Along with the rest of his family, he was killed on the orders of Pol Pot during a 1997 factional split in the Khmer Rouge. Early life Son Sen was born in the village of Huong Hoa, Trà Vinh Province in southern Vietnam to a minor landowning family. Although the Khmer Institute described Sen as being of "Sino-Vietnamese" descent, Béréziat and others have confirmed that like several other Khmer Rouge leaders he was of Khmer Krom ethnicity. From 1946 he attended a teacher training college in Phnom Penh, and in the 1950s received a scholarship to study in Paris, where he became a member of a Marxist group of Cambodian students centred on Saloth Sar (alias Pol Pot), Ieng Sary, and Hou Yuon. Along with other members of the group, Sen was influenced by the radical line pursued by the French Communist Party. Sen's academic record was relatively mediocre, and in May 1956 the authorities withdrew his scholarship due to his continued participation in political activity. Returning to Cambodia with a teaching certificate, he taught for a time at the Lycee Sisowath, and went on to become director of studies of the National Teaching Institute, part of the University of Phnom Penh. By 1960 he had also, however, joined the clandestine Cambodian Communist Party, then known as the Khmer People's Revolutionary Party and led by Tou Samouth. In the maquis Son Sen's political views, which opposed the ruling Sangkum regime of Prince Norodom Sihanouk, were soon to affect his career. In 1962 he was removed from his post at the Institute after being accused of spreading anti-Sangkum ideas amongst the students, though he was permitted to continue teaching and was appointed principal of a high school in Takéo Province. By 1963,