In 1945, Yugoslavia (which is a country on the Balkan peninsula in Europe) wanted to catch people who had been helping the Nazis (who were a powerful group from Germany that had taken over many countries). The Nazis were very cruel and were trying to take over the world. In Yugoslavia, people who helped the Nazis were called collaborators and the Yugoslavs wanted to make sure that nobody was helping the Nazis anymore. So the Yugoslavs searched for anyone who had been helping the Nazis and tried to bring them to justice.