The Tuol Sleng Genocide Museum (Khmer: សារមន្ទីរឧក្រិដ្ឋកម្មប្រល័យពូជសាសន៍ទួលស្លែង; Tuol Sleng (Khmer: ទួលស្លែង Khmer pronunciation: [tuəl slaeŋ]; means "Hill of the Poisonous Trees" or "Strychnine Hill") is a museum chronicling the Cambodian genocide. Located in Phnom Penh, the site is a former secondary school which was used as Security Prison 21 (S-21) by the Khmer Rouge regime from 1975 until its fall in 1979. From 1976 to 1979, an estimated 20,000 people were imprisoned at Tuol Sleng and it was one of between 150 and 196 torture and execution centers established by the Khmer Rouge. On July 26, 2010, the Extraordinary Chambers in the Courts of Cambodia convicted the prison's chief, Kang Kek Iew, for crimes against humanity and grave breaches of the 1949 Geneva Conventions. He died on September 2, 2020 while serving a life sentence.