The young man, identified by government officials as 22-year-old Yasser Esam Hamdi, was captured after a late November prison uprising at Mazar-e-Sharif, the same site where the military seized John Walker Lindh, a Northern Californian who fought for the Taliban.
Hamdi is one of 300 detainees being held at the U.S. naval base at Guantanamo Bay, Cuba, authorities said.
Army Lt. Col. Dan Stoneking, however, cautioned that U.S. authorities have not confirmed that Hamdi was born in the United States.
Stoneking and other government officials noted that most of the detainees are giving false information about their backgrounds. At this stage of their investigation, however, they said Hamdi's claim of U.S. citizenship appears to be valid.
If true, Stoneking said, Hamdi probably would be removed from Guantanamo Bay and placed in the custody of federal law enforcement officials, much like Lindh, who is awaiting trial in Virgina on murder conspiracy charges.
"There is an individual among the detainees in Guantanamo who has indicated his place of birth is Baton Rouge, La.," Stoneking said. "The Department of Justice has recently informed us that they have uncovered a corresponding birth certificate in Baton Rouge.
"However, whether or not that means this detainee is a U.S. citizen may involve some more legal determination. So we're not prepared to answer that at this point."
Stoneking added that "it's our understanding his parents were employed in Louisiana at the time of his birth, and then returned to Saudi Arabia when he was a toddler."
Justice Department officials confirmed that they had found a birth certificate that matched the birth date Hamdi gave U.S. authorities.
Stoneking said he and other authorities at Guantanamo have said that most of the detainees are giving false names to their U.S. interrogators, as well as incorrect information about their pasts. In essence, they said, the detainees are being very uncooperative and making it extremely difficult for the United States to sort them out.
A State Department official said a search of records indicates that Hamdi never applied for an American passport to travel abroad. The official also could not say whether Hamdi had ever applied for a visa to return to the United States.
Lindh is scheduled to go on trial in August. A key part of his defense is that he fought for the Taliban and against the Northern Alliance in Afghanistan, and that he never attempted to betray his country.
Lindh and Hamdi were captured after the prison uprising, which cost the life of the first U.S. casualty in the war against terrorism, CIA officer Johnny "Mike" Spann.