Former German army officer Josef Scheungraber — a lieutenant like Karkoc — was convicted in Germany in 2009 on charges of murder based on circumstantial evidence that put him on the scene of a Nazi wartime massacre in Italy as the ranking officer.
German prosecutors are obligated to open an investigation if there is enough "initial suspicion" of possible involvement in war crimes, said Thomas Walther, a former prosecutor with the special German office that investigates Nazi war crimes.
The current deputy head of that office, Thomas Will, said there is no indication that Karkoc had ever been investigated by Germany. Based on the AP's evidence, he said he is now interested in gathering information that could possibly result in prosecution.
Prosecution in Poland may also be a possibility because most of the unit's alleged crimes were against Poles on Polish territory. But Karkoc would be unlikely to be tried in his native Ukraine, where such men are today largely seen as national heroes who fought for the country against the Soviet Union.
Karkoc now lives in a modest house in northeast Minneapolis in an area with a significant Ukrainian population. Even at his advanced age, he came to the door without help of a cane or a walker. He would not comment on his wartime service for Nazi Germany.
"I don't think I can explain," he said.
Members of his unit and other witnesses have told stories of brutal attacks on civilians.
One of Karkoc's men, Vasyl Malazhenski, told Soviet investigators that in 1944 the unit was directed to "liquidate all the residents" of the village of Chlaniow in a reprisal attack for the killing of a German SS officer, though he did not say who gave the order.
"It was all like a trance: setting the fires, the shooting, the destroying," Malazhenski recalled, according to the 1967 statement found by the AP in the archives of Warsaw's state-run Institute of National Remembrance, which investigates and prosecutes German and Soviet crimes on Poles during and after World War II.