On Monday, a Cambodian court began proceedings against four former leaders of the communist Khmer Rouge regime of the 1970s. The four defendants, now elderly, are the first to face trial. They are charged with crimes against humanity, war crimes, genocide, religious persecution, homicide and torture. They have pleaded not guilty. The UN-backed court was established in 2001 to investigate and try those responsible for the Cambodian genocide that resulted in the death of approximately 1.7 million people, one-third of the Cambodian population, between 1975 and 1979.