It all started on April 17th, 1975 when Khmer Rouge, a communist guerrilla group led by Pol Pot, took power in Phnom Penh, the capital of Cambodia. They forced everybody into the countryside and to labor camps. A large amount of the Cambodian population died about 30% either by starvation or torture. These mass killing lasted for three years until 1979. In 1979, Pol Pot hid to the woods after an invasion by nearby Vietnam which led to the collapse of the Khmer Rouge government. Pol Pot was never brought to justice and died to natural causes while hiding, in 1998.
This picture shows the violent actions to the people from cambodia. You can tell that he has been starved because you can see his bones clearly and looks like he has no energy, in addition you can also tell he has been tortured because of his scars.