John Demjanjuk was heading back to court on Tuesday, where prosecutors will lay out their case accusing him of being accessory to the murder of 27,900 Jews at the Sobibor death camp.
The 89-year-old retired Ohio autoworker rejects the charges and says he has been the victim of mistaken identity and was never at Sobibor.
Prosecutors say Demjanjuk was a Soviet soldier who volunteered to serve the Nazis after he was captured, and was a willing participant in the Holocaust.
The indictment to be read aloud Tuesday alleges Demjanjuk learned how to be a guard at the SS training camp Trawniki, and was then posted to the Sobibor death camp in Nazi-occupied Poland in March, 1943.
If convicted, Demjanjuk faces a possible 15 years in prison.