updated 10:41 AM EDT, Sat March 17, 2012

Berlin (CNN) -- Former Nazi death camp guard and onetime Ohio autoworker John Demjanjuk has died in Germany, a police spokesman said Saturday.

Demjanjuk, 91, was found guilty last May in a German court of assisting in mass murder as a guard at the Sobibor death camp in Poland and sentenced to five years in prison.

He died in a home for the elderly where he was living pending appeal, Oberbayern-Sud police spokesman Kilian Steger said. As part of standard procedure, the Traunstein state prosecutor's office is looking into the circumstances of his death, Steger said.

The Nazis and their sympathizers killed at least 167,000 people at Sobibor in 1942 and 1943, according to the U.S. Holocaust Memorial Museum.

Munich state prosecutors charged Demjanjuk as an accessory to about 27,900 of those deaths, and the court found the killings were "motivated by racial hatred."

Demjanjuk denied the charges, arguing that he was a prisoner of war who was forced to do what the Nazis wanted.

The Ukraine native, who moved to the U.S. after World War II, raised a family and worked in the auto industry in Ohio, was finally extradited from the United States in 2009 to face trial following a long legal battle.

The accusations against Demjanjuk date to the late 1970s, when the U.S. Justice Department accused him of being a Nazi guard known as "Ivan the Terrible." His U.S. citizenship was revoked in 1981, and he was extradited to Israel in 1986.

He was convicted in an Israeli court in 1988 and sentenced to death, but that conviction was overturned in 1993 amid evidence that someone else was "Ivan the Terrible."

A U.S. federal court restored Demjanjuk's citizenship, ruling that the government withheld evidence supporting his case.

But his citizenship was revoked again in 2002 after a federal judge ruled that his 1952 entry into the United States was illegal because he hid his past as a Nazi guard.