By JOHN NOLAN, Associated Press Writer

CINCINNATI (AP) - Retired autoworker John Demjanjuk should be stripped of his citizenship because he served as a guard in Nazi concentration camps, a federal appeals court ruled Friday.

A three-judge panel of the 6th U.S. Circuit Court of Appeals ruled against Demjanjuk in the government's 27-year effort to prove he served as a Nazi camp guard and tried to hide that history.

The court upheld a 2002 decision by a Cleveland federal judge who revoked Demjanjuk's citizenship. The Ukranian-born Demjanjuk, 84, who lives in Seven Hills, insists he was a prisoner during the war, not a guard.

"We find that the plaintiff, the United States of America, sustained its burden of proving through clear, unequivocal and convincing evidence that defendant, in fact, served as a guard at several Nazi training and concentration camps during World War II," Judge Eric Clay wrote. "We concur with the district court that he was not legally eligible to obtain citizenship under the Displaced Persons Act of 1948."

His family vowed to challenge Friday's ruling.

Demjanjuk's age and deteriorating health would make it difficult for him to withstand a process to deport him, said Ed Nishnic, his son-in-law and family spokesman.

"He's slipping. He's not well," Nishnic said. "There are avenues that can be taken to prevent that. That would be the last thing we would like."

The options include asking the full appeals court to reconsider its ruling or asking the Supreme Court to hear the case, Nishnic said by phone from his suburban Cleveland office.

Demjanjuk's attorney, John H. Broadley in Washington, D.C., said he hadn't had a chance to study the ruling.

"Certainly we're going to consider (seeking a) rehearing. We're going to take a careful look at the decision," he said.

Broadley said he hadn't looked into whether any country might be willing to accept a deported Demjanjuk (pictured, above).

Demjanjuk (dem-YAHN-yuk), a refugee from Ukraine who came to the United States in 1952, was originally accused in 1977 by the Justice Department of being "Ivan the Terrible," a particularly sadistic Nazi guard who ran the gas chambers at the Treblinka death camp in occupied Poland.

Between 1942 and 1943, more than 850,000 Jews were murdered at Treblinka. Ivan the Terrible was a guard who herded the victims along the path to the gas chamber, hacking at his victims to speed them along.

Demjanjuk insisted he was the victim of mistaken identity.

He was convicted of war crimes and crimes against humanity and sentenced to be hanged in Israel. Demjanjuk eventually persuaded the Israeli Supreme Court to overturn his conviction based on new evidence that someone else was Ivan the Terrible.

He returned to his suburban Cleveland home in 1993 and avoided publicity. His U.S. citizenship, which had been revoked in 1981, was reinstated in 1998.

But the Justice Department renewed its case, arguing that Demjanjuk was a guard at death camps other than Treblinka. The government no longer tried to link him to Ivan the Terrible.

Keys to the new case were documents kept by the Germans and archived