During the period that Demjunjuk's Israeli conviction was on appeal, the Soviet Union collapsed. New evidence became available in 1991 from behind the former Iron Curtain that strongly indicated that Demjunjuk had not been at Treblinka (and therefore was not "Ivan the Terrible") but had been at other notorious camps, including Trawniki, Sobibor, Flossenburg and Majdaek. Demjunjuk's defense team in the U.S. used this new evidence, along with allegations of improprieties by the OSI, to overturn both the denaturalization decision as well as the later extradition decision. In 1993, the Israeli Supreme court also acquitted Demjanjuk of charges related to the actions of "Ivan the Terrible," even though there was considerable evidence of his being involved with war crimes at other camps. Demjanjuk was freed and, although no longer a U.S. citizen, he was returned to the United States.