At least 200,000 people were executed by the Khmer Rouge (while estimates of the total number of deaths resulting from Khmer Rouge policies, including disease and starvation, range from 1.4 to 2.2 million out of a population of around 7 million). In 1979 Vietnam invaded and toppled the Khmer Rouge regime, which was officially called Democratic Kampuchea.) Wikapedia
The chief Khmer Rouge torturer Kaing Guek Eav (known as Duch and ex-commandant of the notorious S-21 prison) went on trial for crimes against humanity on Tuesday February 17, 2009. It is the first case involving a senior Pol Pot cadre three decades after the end of a regime blamed for 1.7 million deaths in Cambodia.