MIAMI (AP) — Immigration authorities say they are reviewing the case of a U.S. Army veteran and Cuban native who recently discovered he is not an American citizen.

Mario Hernandez served in the Army during the Vietnam War and went on to work for years for the Department of Justice's Bureau of Prisons using a social security number he received when he arrived in the U.S. as a child.

The 58-year-old man always thought he was a U.S. citizen and repeatedly voted. But last year, when he sought a passport to take a cruise with his wife, he discovered the U.S. government did not have him registered as a citizen.

U.S. Citizenship and Immigration Services spokesman Christopher Bentley said in a statement that his agency is reviewing the case and will meet soon with Hernandez and his attorney.

"I served this country," Hernandez said. "I've always tried to prove I'm a good American citizen. ... My parents came for freedom. We owe a lot to this country."

Since the Cuban revolution, those who leave the communist-run island generally get fast-tracked for U.S. residency. Hernandez arrived in 1965 with his mother and always assumed she had filed immigration papers.