John Demjanjuk (b. Iwan Demjanjuk, 1920, Dub Makarenzi , Kazatin subdistrict, Kiev Oblast, Union of Soviet Socialist Republics, now Ukraine) is a retired auto worker who emigrated to the United States from Europe in 1951. He was later accused of and tried for crimes against humanity, based on his being identified by Holocaust survivors in Israel as having been "Ivan the Terrible," a notorious SS guard at the Treblinka extermination camp during the period 1942-1943 who allegedly committed acts of extraordinarily savage violence against camp prisoners.

Demjanjuk was drafted by the Soviet Army in 1940. He and his unit were taken prisoner by Nazi forces in 1942. Demjanjuk's activity between the date of his capture and the end of the war remains unclear. It is what Demjanjuk was doing during this time that forms the basis for the charges that were later filed against him by the US Justice Department and for the war crimes trial in which he was the defendant in Israel.

Demjanjuk became a US citizen on November 14, 1958. He and his wife, whom he met in a displaced persons camp, moved to Indiana with their daughter (they later had two more children) and then to Seven Hills, Ohio, where Demjanjuk became an engine mechanic.

In August 1977, the Justice Department submitted a request to the Northern District Court of Ohio that Demjanjuk's citizenship be revoked on the basis that Demjanjuk had allegedly concealed his involvement with Nazi death camps on his immigration application in 1951. On June 23, 1981, District Court Judge Frank Batisti ruled that Demjanjuk had lied on his application, that he had served as an SS guard at Treblinka and for a brief period at Sobibór, and that he had undergone training at the Trawniki SS training camp.

Demjanjuk's attorneys appealed this ruling. In October 1983, Israel issued an extradition request for Demjanjuk to stand trial on Israeli soil under the Nazis and Nazi Collaborators (Punishment) Law of 1950. Demjanjuk was deported to Israel on February 28, 1986. He was put on trial between February 16, 1987 and April 18, 1988. The prosecution claimed during the trial that Demjanjuk had been recuited into the Soviet army in 1940, and that he had fought against Germany until he was captured by German troops in the eastern Crimea in May 1942.

Demjanjuk was then, according to prosecutors, brought to a Nazi prisoner of war camp in Chelmno in July 1942. Prosecutors claimed that Demjanjuk volunteered to collaborate with the Germans and was sent to the camp at Trawniki, where he was trained to guard prisoners and was given a firearm, a uniform, and an ID card with his photograph. Prosecutors based part of these allegations on the ID card, but defense attorneys countered that the card was forged by Soviet authorities to discredit Demjanjuk. The card was never conclusively established as identifying Demjanjuk as Ivan the Terrible.

Demjanjuk himself testified during the trial in Israel that he was imprisoned in a camp in Chelmno until 1944, when he was transferred to another camp in Austria, where he remained until he joined an anti-Soviet Russian military unit funded by the Nazis until the surrender of Germany to the Allies in 1945.

In February 1988, two Israeli judges sentenced Demjanjuk to death by hanging. Demjanjuk was placed in solitary confinement until August 1993, when five Israeli Supreme Court judges ruled that there was not enough evidence to show that Demjanjuk was Ivan the Terrible.

Their ruling was based partly on the written statements of 32 former guards and 5 former prisoners at Treblinka that Ivan the Terrible's surname was Marchenko, not Demjanjuk. Demjanjuk was released to return to the United States. In 1993, the 6th US Circuit Court of Appeals ruled that Demjanjuk was a victim of prosecutorial misconduct, as federal prosecutors had deliberately withheld evidence), and his sentence was overturned.

In February 1998, Federal District Court Judge Paul Matia ruled that Demjanjuk's citizenship could be restored. On May 20, 1999, the Justice Department filed a new civil complaint against Demjanjuk.

No mention was made in the new complaint of the previous allegations that Demjanjuk was "Ivan the Terrible." Instead, the complaint alleged that Demjanjuk served as a guard at the Sobibór and Maidanek camps in Poland and at the Flossenburg camp in Germany. It additionally accused Demjanjuk of being a member of an SS-run unit that took part in capturing nearly two million Jews in Nazi-occupied Poland. Demjanjuk was put on trial again in 2001, and in February 2002, Matia ruled that Demjanjuk had not produced any credible evidence of his whereabouts during the war and that the Justice Department had proved its case against him.

On May 1, 2004, a three judge panel of the 6th US Circuit Court of Appeals ruled that Demjanjuk could be stripped of his US citizenship because the Justice Department had presented "clear, unequivocal, and convincing evidence" of Demjanjuk's service in Nazi death camps. Demjanjuk vowed to appeal the ruling.