A federal court on Friday revoked the U.S. citizenship of a former Nazi SS member who served as a concentration camp guard.

John Hansl (search), 80, had argued that he freely disclosed he'd been in the German army when he and his family came to the United States in 1955.

Prosecutors said, however, that Hansl failed to reveal he'd been in the SS Death's Head battalion (search) that guarded concentration camps at Natzweiler in France in 1944 and at Sachsenhausen near Berlin in 1943.

Thousands of people were imprisoned and murdered at the two camps.

Hansl's testimony "regarding his personal conduct as a Death's Head guard leaves no room for factual dispute whether he personally advocated or assisted in persecution," U.S. District Judge Robert Pratt (search) wrote.

"He accomplished this by carrying either a machine gun or rifle and standing watch over the camp or over work-details outside the camp," Pratt wrote, adding Hansl admitted to assisting in the search for an escaped prisoner, "who ended up being shot."

Hansl's lawyer, Lisa Mattsson, said the ruling will be appealed. She said the court did not sufficiently review new evidence that was presented.

Hansl, of German descent, was born in Croatia in 1925. When he was 18, he was drafted in the Nazi Waffen SS in 1943. He admits he served as a perimeter guard at the Sachsenhausen Concentration Camp (search) near Berlin. He was later transferred to the front lines, where he was captured by the Allies.

Hansl, his late wife, Anna, and their children emigrated from Austria. Hansl and his wife became citizens in 1961; the children were granted citizenship the following year.

More than 70 people who assisted in Nazi persecution have been stripped of U.S. citizenship since the Office of Special Investigations began operations in 1979, according to the Justice Department. There are about two dozen additional cases currently in litigation.

A message left Friday at the Justice Department's Office of Special Investigations, which handles such cases, was not immediately returned.