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.
"Later, when we were passing in file through the destroyed village," Malazhenski said, "I could see the dead bodies of the killed residents: men, women, children."
In a background check by U.S. officials on April 14, 1949, Karkoc said he had never performed any military service, telling investigators that he "worked for father until 1944. Worked in labor camp from 1944 until 1945."
However, in a Ukrainian-language memoir published in 1995, Karkoc states that he helped found the Ukrainian Self Defense Legion in 1943 in collaboration with the Nazis' feared SS intelligence agency, the SD, to fight on the side of Germany — and served as a company commander in the unit, which received orders directly from the SS, through the end of the war.
It was not clear why Karkoc felt safe publishing his memoir, which is available at the U.S. Library of Congress and the British Library and which the AP located online in an electronic Ukrainian library.