Former Nazi death-camp guard John Demjanjuk died at the age of 91 in a German home for the elderly on Saturday, a police spokesman confirmed to CNN. Demjanjuk, who was known as "Ivan the Terrible" in his Nazi days and had been living in the U.S. since the early 1950s, was accused in the 1970s for his involvement in the deaths of 28,000 Jews at the Sobibor camp in Nazi-occupied Poland. After his U.S. citizenship was revoked in 1981, Demjanjuk was extradited to Israel and sentenced to death, but the sentence was overturned amid evidence that someone else was Ivan the Terrible. He spent his later life fighting charges of mass murder, claiming he had himself been a Nazi prisoner of war. He was found guilty in Germany last May and sentenced to five years in prison, but was released because of his advanced age.