John Demjanjuk, a retired U.S. engine mechanic convicted for his role in killing 28,000 Jews as a guard at a Nazi death camp during World War Two, died on Saturday aged 91 in a care home in Germany, police said.
Once top of the Nazi-hunting Simon Wiesenthal Center's list of most wanted Nazi criminals, Ukrainian-born Demjanjuk denied the charges against him, saying he was drafted into the Soviet army in 1941 and then taken prisoner by the Germans.
A Munich court convicted 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.
He died in the early hours of Saturday at the care home near Rosenheim, south of Munich, where he had been living, Bavarian police said.
His passing brings us closer to the day when the Holocaust moves from lived memory of survivors and perpetrators into history, said Lawrence Douglas, a professor of law at Amherst College in the United States who has written about the Demjanjuk case and other war crimes trials.
Demjanjuk was extradited to Germany from his home in the United States in 2009 to stand trial in Munich - birthplace of Adolf Hitler's Nazi movement.
He attended the 18-month court proceedings in a wheelchair and sometimes lying down, speaking only to deny the charges.
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.
It was the first time a German court recognised the role played by auxiliaries in making genocide possible, said Douglas.
Demjanjuk's defence attorney tried to suggest there was something fundamentally unfair holding a relatively minor figure when more superior officers escaped being brought to justice, Douglas said.
That one of the last trials (linked to the Nazi era) involved such a minor figure in no way detracts from the justice of the case, added Douglas.
His comments were echoed by Dalia Domer, a retired member of Israel's Supreme Court which tried Demjanjuk in an earlier trial that resulted in his acquittal.
The importance of everything that happened was in how it put on the table once more the things that were done (to the Jews). The main thing is that it is not forgotten, that humanity learns a lesson from this, she told Israeli television.
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.
Defence attorneys said the card was a Soviet-made fake.
An appeal by his lawyers against the guilty verdict was pending at the time of his death.
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.
That 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 United States in the early 1950s and became a naturalised citizen in 1958, changing his name to John from Ivan and working as an engine mechanic at a factory in Ohio.
A judge later revoked his U.S. citizenship because of his past as a Nazi camp guard, leaving him stateless.
(Additional reporting by Dan Williams in Jerusalem; Writing by Gareth Jones; Editing by Karolina Tagaris)