Today marks 50 years since Phnom Penh fell to the Khmer Rouge. On April 17, 1975 tanks rolled into the Cambodian capital and the people thought the long-running civil war was over. Instead, it was the start of one of the worst genocides of the 20th century. During a brutal four-year period, the communist-nationalist Khmer Rouge killed between 1.6 and 3 million people via execution, starvation and forced labour. The outside world had few clues of these horrors but American journalist Elizabeth Be