A German prosecutor investigating Nazi war crimes is recommending murder charges be brought against a 94-year-old who lives in the United States on suspicion he ordered his unit to attack a Polish village in 1944, killing about 40 civilians.

Ukrainian-born Michael Karkoc, who immigrated to the United States in the late 1940s, is suspected of having led the killings in the village of Chlaniow, according to news reports that prompted German and Polish investigations.

"I came to the conclusion that he was in charge during a crime in Chlaniow," Thomas Will, deputy head of the central office investigating Nazi crimes, told Reuters on Monday. "The charge would be about 40 counts of murder."

Karkoc's son, Andrij Karkos, who speaks for the family, wrote in the Star Tribune newspaper in Minneapolis in July, when the allegations were first reported: "My father is not a criminal, and never was."

He also said in a statement to reporters at the time: "My father was never a Nazi." He said the family would make no further comment on the matter until it had the opportunity to review any documents relating to it.

Karkos could not be reached Monday for comment on the German prosecutor's remarks.

Will's office investigates crimes committed under Adolf Hitler and then makes recommendations to the appropriate public prosecutors to open cases, usually between 20-40 times a year.

Will said the case may be difficult to bring to court as Karkoc was not German, did not live in Germany and the alleged the crime did not take place there - meaning Germany's highest appellate court for civil and criminal cases may have to decide where it should be prosecuted.

A spokesman for the U.S. Justice Department, Peter Carr, said the department was aware of the allegations.

"We generally do not confirm nor deny whether an individual is under investigation," he said.

Karkoc was born in 1919 in a village in western Ukraine, according to the commentary his son, Karkos, who spells his family name differently to his father, wrote for the Star Tribune.

He was in Poland when he was conscripted into the German army in late 1940, according to his son. Karkoc took part in the invasion of Ukraine, later deserting the German army and joining the Ukrainian nationalist underground.

The retired carpenter has lived for several decades in a Minneapolis neighborhood that is a hub for immigrants from Ukraine.

