John Demjanjuk, convicted last year for his role in killing 28,000 Jews at a Nazi death camp during World War Two, has died aged 91.
A Munich court convicted Ukrainian-born Demjanjuk in May 2011 of helping to kill the Jews at the Sobibor death camp in Nazi-occupied Poland.
He was sentenced to five years in prison but freed because of his age.
The Bavarian police said in a statement Demjanjuk had died in the early hours of Saturday at the care home near Rosenheim, south of Munich, where he had been living.
Demjanjuk was extradited to Germany from his home in the United States in 2009 to stand trial. He attended the 18-month court proceedings in Munich - birthplace of Adolf Hitler's Nazi movement - in a wheelchair and sometimes lying down.
He denied the charges against him but otherwise did not speak at his trial. The court verdict said guards had played a key role at extermination camps like Sobibor, where at least 250,000 Jews are thought to have been killed despite only 20 German SS officers being there.
Once top of the Nazi-hunting Simon Wiesenthal Centre's list of most wanted Nazi criminals, Demjanjuk said he was drafted into the Soviet army in 1941 and then taken prisoner by the Germans.
Prosecutors had faced several hurdles in proving Demjanjuk's guilt, with no surviving witnesses to his crimes and heavy reliance on wartime documents, namely a Nazi ID card indicating he had worked at Sobibor.
Demjanjuk was initially sentenced to death two decades ago in Israel for being the so-called "Ivan the Terrible" camp guard at Treblinka in Poland.
The guilty verdict was overturned on appeal by Israel's supreme court in 1993 after new evidence emerged pointing to a case of mistaken identity.
Demjanjuk emigrated to the US in the early 1950s and became a naturalised citizen in 1958, working as an engine mechanic in Ohio.
Reuters