Genocide Museum (S-21) served as the central hub of a vast prison system throughout the country and was used throughout the period as a secret facility for the detention, interrogation, torture, and extermination of those deemed “political enemies” of the regime. Due to a policy of guilt-by-association, at times whole families were detained at the center. Very few inmates were released from the prison during the years 1975 and 1979. Only 12 former inmates survived the opening of S-21 when Phnom Penh was liberated. Four of them were children. Killing Field between 1975 and 1979 by the Khmer Rouge in perpetrating the Cambodian genocide. Situated about 17 kilometers (11 mi) south of the city center, it was attached to the Tuol Sleng detention center. The bodies of 8,895 victims were exhumed from the site after the fall of the Rouge, who would have been executed there—typically with pickaxes to conserve bullets—before being buried in mass graves.