Germany said Monday it has opened a formal preliminary investigation of Michael Karkoc, a Minnesota man, who allegedly was a former commander of a Nazi SS-unit during World War II.
Prosecutors are trying to determine whether there is enough evidence to seek his extradition back to Germany.
Kurt Schrimm, the head of Germany’s special office investigating Nazi war crimes, said they must first determine whether there is enough proof to charge Karkoc.
More from GlobalPost: Report: Nazi commander Michael Karkoc living in US since World War II (VIDEO)
An Associated Press investigation found Karkoc, now 94 years old, lied to immigration officials about his past when he entered the United States in 1949.
At the time he told authorities he had performed no military service during the war.
However, the AP investigation found he was a member of the Ukrainian Self Defense Legion, which fought with the Nazis in the Ukraine and Poland; and that he served in the SS Galician Division during the 1944 "Warsaw Uprising."
University of Minnesota law professor Fred Morrison said the next step for German investigators is to establish the 94-year-old held "command responsibility" during the 1944 Uprising.
Under German law, given the statute of limitations, Karkoc can only be charged with murder or accessory to murder.
Andriy Karkos, Karkoc's son, maintains his father "was never a Nazi."