By Jane Sutton
MIAMI (Reuters) - A prisoner was found dead of undetermined causes at the Guantanamo Bay U.S. naval base where foreign captives have been held since shortly after the September 11 attacks, the U.S. military said on Monday.
The unidentified prisoner, whose name and nationality were not disclosed pending notification of family, died on Saturday, military officials said. He was the ninth captive to die at the detention camp since it opened in 2002.
The dead man was not among the small group currently facing charges in the war crimes tribunal at the Guantanamo base in eastern Cuba, and he had not been designated as eligible for prosecution, said Navy Captain Robert Durand, a spokesman for the detention operation.
About half of the Guantanamo detainees have been cleared for release, but it was not known if he was among that group.
Guards found the man "motionless and unresponsive" during a routine check, he said. Medics tried to revive him and took him to the base hospital, where he was pronounced dead, Durand said.
His remains will be returned home after an autopsy, and the Naval Criminal Investigative Service is investigating the death, he said.
The man died in Camp 5, a maximum security facility that holds those accused of breaking camp rules. He was "in disciplinary status" after recently assaulting a guard with a "cocktail" of bodily fluids, Durand said.
The prisoner had previously been a hunger striker whose weight dropped low enough that he was force-fed nutritional supplements, though he sometimes ate food while on a hunger strike, Durand said.
"He declared himself to be no longer a hunger striker on June 1, but continued to be medically monitored," Durand said. "Recently, his weight was recorded at 95 percent of his ideal body weight, and 14 pounds heavier than he was when he arrived at Guantanamo."
The detention camp was set up to hold non-American captives suspected of involvement with al Qaeda, the Taliban or other Islamist militant groups after the September 11, 2001, attacks. Of the 779 men held there, 167 remain.
Two of the earlier deaths were from natural causes and six were designated as suicides, most of them by hanging.
As news spread of the latest death, the mood among the other prisoners was "sadness and quiet and reflecting," Durand said.
"It's been fairly subdued," he said. "There haven't been any disturbances."
(Editing by Doina Chiacu and Eric Beech)