The prosecution of former Khmer Rouge members is happening now. In case you don't know, the Khmer Rouge was responsible for one of the bloodiest pogroms in recent history. Pol Pot killed over a million innocent people in Cambodia.
It's good to know that the people involved in the massacres will be brought to justice. No should get away with engineering a massacre. Trials like these are why so many idealistic law students study international law.
FYI: there is a 1984 movie about the massacre aptly titled, The Killing Fields.