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Tuol Sleng Genocide Museum is a museum of genocide crimes from the Khmer Rouge during its ruling between 1975 and 1979. It was the secondary school before becoming a concentration camp of the red Kmmer genocide regime. In 1975, the school was converted to a prison called security prison S21. During the 4-year ruling of the Red Kmer, the site was imprisoned between 17,000 people (other sources for the teeth were 20,000), most of which were members or previous troops of the red Kmer convicted of betrayal. The school was renovated as a power fence, reinforced the room of the detention hall, ask room and torture room.