Operation Last Chance assisted in the prosecution and interim conviction of John Demjanjuk for his alleged role in the torture and murder of Jews in various concentration camps, among other atrocities. Demjanjuk became an American citizen in the 1950s. Demjanjuk had previously been exonerated of genocide and crimes against humanity by Israel's Supreme Court. Demjanjuk was later accused by Germany of being a Ukrainian collaborator (sometimes referred to by camp inmates as "Askaris") and camp guard at Sobibor. In May 2011, a Munich lower criminal court found Demjanjuk guilty of being an accessory to murder at Sobibór extermination camp, where about 250,000 Jews were put to death. Demjanjuk denied all accusations and appealed the verdict. Shortly after Demjanjuk's death in 2012, the German Appellate Court announced that, because Demjanjuk died before his appeal could be heard, Demjanjuk had no criminal record, that his previous interim conviction by a lower court was annulled, and that Demjanjuk was innocent.