Joseph Stalin, and Pol Pot, who declare that 1975 was 'Year Zero' and directed a ruthless program to "purify" Cambodian society of capitalism, Western culture, religion and all foreign influences in favour of an isolated and totally self-sufficient Maoist agrarian state. No opposition was tolerated.
I am not sure they did realise they were destroying Cambodia, Vietnamese troops invaded Cambodia, capturing Phnom Penh on January 7, 1979 and deposed the Khmer Rouge regime. And although controlled a small area near the Thai border, the Khmer Rouge effectively ceased to exist in December 1999.
In May 2006 Justice Minister Ang Vong Vathana announced that Cambodia's highest judicial body approved 30 Cambodian and U.N. judges to preside over the long-awaited genocide tribunal for surviving Khmer Rouge leaders. The judges were sworn in early July, with trials expected to start mid-2007