(CNN) -- A detainee who was found dead over the weekend at the U.S. military prison at Guantanamo Bay, Cuba, was identified as Adnan Farhan Abdul Latif, 32, of Yemen.
U.S. Southern Command released his name Tuesday after notifying his family.
Latif had been detained at Guantanamo since January 2002.
The detainee was found unresponsive Saturday afternoon during a routine check, Southern Command said. Lifesaving measures were performed, but the detainee died at the hospital.
An autopsy was conducted, Southern Command said Tuesday, though it will be some time before the results are known.
The cause of death is under investigation. Suicide has not been ruled out, according to Southern Command Sgt. Shanda De Anda.
Considered a foot soldier and one of Osama bin Laden's Yemeni bodyguards, Latif is mostly known for his legal fight for his freedom.
In June, appeals from him and six other detainees contesting their open-ended custody were turned aside by the Supreme Court.
A federal judge had ordered Latif's release, but the appeals court subsequently concluded that he was part of the al Qaeda terror group and that the government could detain him indefinitely.
His lawyers say he went to Afghanistan and Pakistan for medical treatment for a head injury, but the U.S. military -- without revealing too many specifics publicly -- said he was there to train as a terrorist in a remote al Qaeda camp.
CNN's Bill Mears and Tim Lister contributed to this report.