The pictures on this link were taken at Choeungek genocidal centre (one of the many Killing Fields) and S21 - a converted school used for torture. Once its victims confessed, they were then sent to the Killing Fields. There, they were killed by being battered with iron bars, pickaxes, machetes and many other makeshift weapons. Victims of the Khmer Rouge were seldom shot as bullets were viewed as too precious for this purpose.
Quite how this was allowed to continue for years during our lifetime beggars belief. Even though the vast majority of the victims were Cambodian, foreigners were also imprisoned, including Vietnamese, Laotians, Indians, Pakistanis, Britons, Americans, New Zealanders and Australians.