Lawyers for an 87-year-old Horner Park man who faces deportation for aiding the Nazi Party in Ukraine during World War II argued Thursday that he never belonged to an organization linked to the Nazis.

Osyp Firishchak's citizenship was revoked in 2004 after he was accused of belonging to the Ukrainian Auxiliary Police, an arm of the Nazi Party. According to court documents, the UAP "rounded up Jews, imprisoned them in a ghetto, terrorized them, oversaw their forced labor . . . and delivered [them] to killing sites for mass execution."

Firishchak's attorney, James Maher III, argued before the 7th U.S. Circuit Court of Appeals that Firishchak did not belong to the UAP and did not lie to immigration officials about his background when he became a U.S. citizen in 1954.

Maher also argued that the government did not meet the burden of proof in showing that documents linking Firishchak to the UAP were authentic.

Judge Terence T. Evans noted that the documents had Firishchak's name, town and date of birth on them. If they weren't authentic documents, the judge asked, "what do you think they are?"

"I think the government failed to prove what they are," Maher replied.

Jeffrey Menkin, an attorney with the office of special investigations of the U.S. Department of Justice, argued that "all members [of the UAP] took part in massive, massive operations to round up tens of thousands of Jews."

Menkin said the operations took place in L'viv, Ukraine, and that documents show Firishchak participated in searching for other policemen who did not report for duty.

Menkin also said Firishchak identified his own signature on seven documents in interviews with authorities.

"[He] acknowledged that he signed the documents," Menkin said. Menkin also said this case offered "more documents than any other Nazi war crimes case." The disputed documents "were certified by state archives in L'viv and the U.S. Embassy in Kiev, Ukraine," according to Menkin.

Firishchak moved to the United States in 1949. In his immigration interview , he listed his occupation during the war as "laborer." In Chicago, he worked as a carpenter.

If Firishchak loses his appeal and is denaturalized as a citizen, he will face deportation.

The 7th Circuit will issue a ruling at a later date.