WARSAW (Reuters) - Poland plans to seek the extradition of an American on suspicion of committing crimes against humanity in the World War Two deaths of 44 Polish villagers, Poland’s government-affiliated history institute said on Monday.

The man, identified as Michael K., is suspected of ordering the killings in 1944 in eastern Poland when he was a commander in the Nazi’s SS-led Ukrainian Self Defence Legion, the Institute of National Remembrance (IPN) said in a statement.

As a result of that order, several villages - including Chlaniow and Wladyslawin - were set on fire and buildings destroyed, the IPN said.

“In our investigation Michael K. is the main suspect. We are convinced that this person, living in the United States, was the person who carried out the pacification of (the villages),” Robert Janicki, a prosecutor with the IPN, told Reuters. “All the evidence we have gathered, mainly the documents we have collected, give us this certainty.”

The IPN has asked a regional court in the Polish city of Lublin to issue an arrest warrant for Michael K. as the first step toward an extradition request.

Janicki would not reveal Michael K.’s last name, due to privacy laws, but he was identified by the Associated Press as Michael Karkoc, who lives in Minnesota.

An article by the news agency in 2013 detailing Karkoc’s connections to the Nazis and his move to the United States, spurred investigations in Germany and Poland into Karkoc’s role during World War Two.

Karkoc’s family had repeatedly denied that he was involved in any war crimes, the AP said. The news agency reported Monday that Karkoc, now 98, is suffering from Alzheimer’s disease, according to his family.

Karkoc could not be reached for comment by Reuters.

Karkoc’s age would not stop investigators, Janicki said.