Australian David Hicks, the first prisoner to face a new US war crimes tribunal, unexpectedly pleaded guilty on Monday to a charge of helping Al-Qaeda fight American troops and their allies during the US-led invasion of Afghanistan.
Hicks entered his plea following the first day of hearings in the military tribunals created by Congress after the Supreme Court struck down an earlier version that President George W Bush authorised to try foreign captives on terrorism charges.
Hicks, who has been held at Guantanamo for more than five years, could learn his sentence by the end of the week and could be back in Australia by the end of the year, said the chief prosecutor for the tribunals, Air Force Col. Moe Davis.
"This is the first step toward David returning to Australia," said one of Hicks' Australian lawyers, David McLeod.
Hicks, a 31-year-old former kangaroo skinner, had faced life imprisonment if convicted on the charge of providing material support for terrorism.
His guilty plea will bring a more lenient sentence and the judge ordered the prosecutors and defense lawyers to draw up a plea agreement by 4 pm EDT (2000 GMT) on Tuesday.
Under a long-standing diplomatic agreement, Hicks will serve his sentence in Australia.
He will admit to only some of the allegations in the broadly written charge, which accused him of attending Al-Qaeda training camps, conducting surveillance on the American embassy in Kabul, taking up arms to guard a Taliban tank, and fighting against US forces and their allies in Afghanistan.
He was captured there in December 2001 and sent to Guantanamo a month later.
"At some point he will have to verbalise to the judge what he did and why he's guilty of the offense," Davis said.
Hicks appeared before the tribunal judge on Monday. Five US military officers who comprise the rest of the tribunal will be brought to the base by the end of the week to hear Hicks' formal plea and decide his sentence.
Hicks, who wore a khaki prison uniform and was unshackled during the hearing, has grown his hair to chest-length and looked far older and chubbier than at his last hearing in 2004.
He was allowed to meet privately in the court building with his father, Terry Hicks, and sister Stephanie, who were flown to the base by the US military for Monday's hearing.
"He's really changed a lot in three years," said the elder Hicks, who had last seen his son at the 2004 hearing.
Hicks, the first of the 385 Guantanamo prisoners to be charged in what are formally called military commissions, wants only to return to Australia, settle down and see his two children, his father said.
His lawyers said they could not discuss what prompted Hicks' decision until after the agreement is final.
But McLeod had said on Sunday that Hicks was convinced he could not get a fair trial and expected to be convicted even if he defended the charges.
Hicks initially said he would defer entering a plea until a future hearing. His military lawyer Marine Maj Michael Mori later told the court that Hicks had changed his mind.
Hicks answered "yes, sir," when the judge, Marine Col Ralph Kohlmann, asked him to confirm the guilty plea.
Hicks has said he was sodomised, beaten, and subjected to forced injections while in US custody, allegations the military calls untrue and nonsense.
Rights activists and foreign governments have long criticised the prison camp on the eastern tip of Cuba for what they say are abuses of detainees' rights.
Washington contends the prison system is necessary to hold foreign suspects captured in the war on terrorism it declared after the September 11 attacks.
Legal and human rights monitors observing the hearings said the tribunals were rigged to ensure convictions and allow evidence obtained through coercion.
The tribunals are already the subject of new court challenges.