(CNN) -- The founder of the Simon Wiesenthal Center wants the Justice Department to investigate allegations that a Minnesota man commanded a Nazi unit accused of war crimes in World War II.
Rabbi Marvin Hier sent a formal letter to the department Friday saying he wants an immediate inquiry to find out whether 94-year-old Michael Karkoc should be brought to justice.
The Associated Press reported Friday that Karkoc lied to American immigration officials in 1949 in order to gain entry to the United States and that he has been living in Minnesota since shortly after the war.
Karkoc told U.S. authorities he was a carpenter and performed no military service during the war, even though records show he was a commander of the SS-led Ukrainian Self Defense Legion, according to an investigation by the Associated Press.
Members of that unit have described carrying out brutal attacks on civilians, including the destruction of a village that killed more than 40 men, women and children, the AP reported.
Karkoc's son forcefully denied the AP report, saying Friday the news agency "intentionally and maliciously defamed" his father by publishing the story.
"To quote AP, 'Records do not show that Karkoc had a direct hand in war crimes.' End quote. And that's the God's honest truth. My father was never a Nazi," Andriy Karkos told reporters in Minneapolis.
Read: Recovered Nazi Diary gives rare view into Third Reich
Efrain Zuroff, who directs the Wiesenthal Center's Israel office, told CNN he was aware of the investigation into Karkoc's whereabouts before the AP story was published, though he did not elaborate. Zuroff has spent decades tracking and pursuing alleged Nazi war criminals.
"There is no doubt it's him," Zuroff said. "The question now is, what action will be taken by the U.S. authorities?"
A Justice Department spokesman told CNN it is aware of the media reports about Karkoc, an ethnic Ukrainian.
"While we do not confirm or deny the existence of specific investigations, I can say as a general matter that the Department of Justice continues to pursue all credible allegations of participation in World War II Nazi crimes by U.S. citizens and residents," spokesman Michael Passman said.
Among the documents uncovered by the AP was a Ukrainian-language memoir written by Karkoc and published in 1995 in which he is oddly frank about his involvement in the war.
Karkoc says he helped found the Ukrainian Self Defense Legion in 1943 in collaboration with the Nazis' SS intelligence agency to fight on the side of Germany. He says the unit received orders directly from the SS.
The Ukrainian Self Defense Legion was folded into the SS Galician Division in 1945, and Karkoc wrote that he remained with it until the end of the war.
Both groups were on a secret U.S. government blacklist of organizations whose members were forbidden from entering the United States at the time, Hier says.
Though records cited by the Associated Press do not reveal that Karkoc had a direct hand in war crimes, statements from men in his unit and other documentation confirm the Ukrainian company he commanded massacred civilians.
In 1944, in retaliation for the killing of an SS officer by anti-Nazi Polish resistance fighters, the unit was directed to "liquidate the residents" of the village of Chlaniow, according to a 1967 statement by one of Karkoc's men, which was found by the AP.
"It was all like a trance: setting the fires, the shooting, the destroying," Vasyl Malazhenski says in the statement. When the unit passed through the destroyed village later, he said, "I could see the dead bodies of the killed residents: men, women, children."
According to Hier, Karkoc's unit also was involved in numerous atrocities during the 1944 Warsaw Uprising, in which the Nazis brutally suppressed a Polish rebellion against German occupation.
Zuroff said accused Nazi war criminals cannot be tried in the United States because the alleged crimes happened outside the country, but they can be tried for immigration and naturalization violations.
"The first step would be denaturalization, assuming (Kurkoc) has U.S. citizenship, which would be followed by several possible scenarios," Zuroff said.
Those include deportation or extradition to Germany or Poland, which Zuroff said are the only two countries that might seek his extradition.
Poland's Institute of National Remembrance, which prosecutes war crimes against the Polish people, said Friday it will help the United States gather evidence to determine the facts about Karkoc's alleged role in the war.
In Minneapolis, where Karkoc lives in a modest home in the northeast part of the city, neighbors reacted in disbelief about a man known to them only as a devoted husband and father.
"I couldn't believe it," Gordon Gnasdoskey told CNN affiliate KARE. "He's never said a bad word. I've never had any trouble with him. Just a good neighbor."