Bronislaw Hajda, 73, a retired factory worker living in Schiller Park, Ill., served as an armed guard for the SS training camp Trawinki, the Treblinka labor camp and the SS Streibel Battalion.

The judge found that he "unquestionably" participated in the massacre carried out by the guards when the Nazis liquidated Treblinka in 1944 as Allied forces approached. On that day, hundreds of Jewish prisoners were shot at point-blank range in a pit by the camp guards.

After the liquidation, Hajda joined the SS Streibel Battalion, which forcibly conscripted Polish civilians as slave laborers to build military fortifications.

Hajda had told immigration officials that he spent most of the war working as a shoemaker. At his trial last month, he said he was a victim of misidentification.

A U.S. official said the government would now seek to have Hajda deported.