Polish officials are seeking the arrest of a Minnesota man they say was a Nazi commander during World War Two.
Michael Karkoc, 98, is accused of ordering the killing of 44 Poles while he allegedly led a unit in the SS-led Ukrainian Self Defence Legion.
Polish prosecutor Robert Janicki said that evidence collected from years of investigation confirmed his identity "100%".
Mr Karkoc's family has denied he was involved in any war crimes.
Prosecutors from the Polish government-affiliated National Remembrance Institute have asked a regional court in Lublin to issue a warrant for Mr Karkoc's arrest.
If granted, Poland would seek to extradite Mr Karkoc to face trial.
"He is our suspect as of today," Mr Janicki said.
The Minneapolis resident is accused of killing civilians in the villages of Chlaniow and Wladyslawin in July 1944.
If convicted, he could face life in prison.
Mr Karkoc was previously investigated by German authorities in 2013 after the Associated Press reported he was a former Nazi commander in the SS-led unit, which was accused of burning villages and killing civilians in Poland.
The investigation was halted in 2015 after prosecutors said they received "comprehensive medical documentation" showing he was not fit to stand trial.
Mr Karkoc's son, Andriy Karkoc, said his father was not in Poland and was not behind any war crimes.
He said that stories about his father are "misinformation or disinformation" created by Russian President Vladimir Putin's government.
Efraim Zuroff, a top Nazi hunter at the Simon Wiesenthal Center, commended Polish authorities for taking legal action.
Mr Zuroff told the AP that "it's high time that the Poles became more active seeking people who committed crimes in World War Two on Polish soil".