A Saudi Arabian captive committed suicide at the U.S. detention center in Guantánamo Bay, Cuba, on Wednesday -- almost a year after the first suicides at the five-year-old detention center.

The U.S. Southern Command announced the death Wednesday evening, declining to identify the dead man and saying a Navy investigation into the circumstances had already begun.

The man "was found unresponsive and not breathing in his cell by guards. The detainee was pronounced dead by a physician after all lifesaving measures had been exhausted."

The military declined to elaborate on whether the man imitated the method of two Saudis and a Yemeni men who were found hanged in separate single cells on June 10, 2006. They had made nooses from bedsheets. The three men were incarcerated on the same cell block.

The United States holds about 80 Saudi citizens at Guantánamo. They include two Saudi men who had been held in secret CIA custody and were moved to the base last year as so-called high-value detainees, by order of President Bush.

The most famous captive held there, alleged self-confessed 9/11 mastermind Khalid Sheik Mohammed, is not Saudi.

Another long-held Saudi captive has been on a hunger strike since October 2005, force-fed through a tube in his nose.

The death occurred just one week after Navy Rear Adm. Harry Harris handed off command of the prison camps to Rear Adm. Mark Buzby. Harris caused an international stir by declaring the suicides last year as an act of "asymmetric warfare" waged by weak al Qaeda captives against an overwhelming force, their U.S. captors.

Lawyers for the men blamed the deaths on despair.

Anant Raut, of Washington, D.C., who represents five captives at Guantánamo in federal courts for several years, called for a reevaluation of conditions at the base, where most captives live in single cells.

He said "as a simple matter of human decency" the United States should abandon its policy of indefinite detention without charge of the vast majority.

Of the 380 or so Muslim captives there, only three have been charged.

"If we're not going to charge them with anything, send them home, " said Raut. "Don't lock them in a hole and take away their hope."

The suicide also occurred five days before a session of the Pentagon's Military Commissions is supposed to formally charge Canadian Omar Khadr, 20, with the 2002 grenade killing of a U.S. soldier in Afghanistan.

But Khadr's Pentagon appointed attorney, Marine Lt. Col. Colby Vokey, said late Wednesday he would not be attending the 8 a.m. session on Monday because Khadr had fired all his American attorneys, both civilian and military.

"He doesn't trust American lawyers, and I don't particularly blame him, " Vokey said. "The United States is responsible for his interrogation and his treatment under a process that is patently unfair."

Khadr, the Toronto-born scion of a fundamentalist Muslim family, has been in U.S. custody since his capture in a firefight in Afghanistan in 2002 at age 15.

He met with two family lawyers from Canada last week, and told them he was firing Vokey and a team of American University law professors who have been suing on his behalf in federal court.

Vokey said late Wednesday in an e-mail that the Pentagon's chief defense counsel, Marine Col. Dwight Sullivan, had relieved him of the duty to defend Khadr -- and that, without a client, Vokey would not be at the hearing.