The Killing Fields are a number of sites in Cambodia where large numbers of people were killed and buried by the communist Khmer Rouge regime, during its rule of the country from 1975 to 1979, immediately after the end of the Cambodian Civil War.

Estimates of the total number of deaths resulting from Khmer Rouge policies, including disease and starvation, range from 1.7 to 2.5 million out of a 1975 population of roughly 8 million.

The Khmer Rouge regime arrested and eventually executed almost everyone suspected of connections with the former government or with foreign governments, as well as professionals and intellectuals.

Tuol Sleng is a former high school which was used as the notorious security prison 21 (S-21) by the Khmer Rouge. It was one of at least 150 execution centers in the country, and as many as 20,000 prisoners there were later killed.

The prisoners were photographed before being locked up and little did they know about their fate. Some of them even gave their best smile to the camera as if posing for the school photographer…