A separatist rebel who killed two American teachers at a U.S.-owned gold mine in Indonesia's easternmost province of Papua was sentenced to life in prison Tuesday and his accomplices up to seven years, a judge said.

The defendants — all indigenous Papuans — have repeatedly called their trial a sham and walked out in protest hours before the verdicts were read.

Prosecutors claimed the men were all members of a small rebel army fighting for a separate state in the resource-rich province.

They were accused of launching a 30-minute assault on a convoy heading toward a mine owned by Freeport-McMoRan Copper and Gold Mine Inc. that killed Rick Spier, 44, of Littleton, Colorado, Ted Burgon, 71, of Sunriver, Oregon, and an Indonesian teacher.

Eight other Americans, including a 6-year-old girl, were seriously wounded in the Aug. 31, 2002 attack that initially complicated ties between Washington and Jakarta.

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Judge Andriani Nurdin said the ringleader, Antonius Wamang, 31, deserved life behind bars, even though prosecutors demanded only 20 years.

"This was premeditated murder. It was a gross violation of human rights," she told the Central Jakarta District Court, later sentencing two other men to seven years for taking part in the ambush and four others to 18 months for providing logistical support.

The defendants have remained silent throughout their five-month trial, refusing to make a defense plea and regularly walking out of the courtroom, saying the judges were biased against them.

Their lawyer, Johnson Panjaitan, claimed Tuesday that he had not been allowed to meet with his clients for more than a month, but court officials could not immediately confirm that.

"Can you imagine that a client cannot communicate with his lawyer?" he asked.

But Spier's widow, Patsy, who suffered two gunshot wounds in the attack, hailed the ruling, saying she was "firmly convinced Wamang and the other defendants are guilty of this horrific and cowardly act of terrorism."

"Wamang even admitted his role in the killings," she said in an e-mail to reporters.

Wamang — indicted by a U.S. grand jury in 2004 for the murders — has acknowledged being a Papuan separatist and said he shot at the convoy because he thought it was carrying soldiers.

But the other men maintain they were innocent civilians.

"We had nothing to do with these shootings," said Ishak Onawame, 54, before the verdicts were read out. "Our trial has been manipulated for the interests of two countries, Indonesia and the United States."

Dozens of Papuan student protesters gathered outside, chanting "Release them! Release them!"

Indonesian security forces guarding the mine were initially suspected of taking part in the killings to extort higher protection payments from the New Orleans-based company.

Washington made Indonesian cooperation with the FBI probe into the killings a condition of restoring military ties with Jakarta last year that had been frozen since 1999 due to human rights concerns.

Many in Washington were keen to re-engage with the military, which they see as vital in the country's fight against terrorism.

Indonesian journalist Andreas Harsono and U.S. researcher Eben Kirksey said, however, following a two-year investigation into the attack, that the military's role could not be discounted.

"The attack took place less than a kilometer from a military checkpoint, but it took soldiers more than an hour to respond," Harsono said, adding while prosecutors claimed the separatists had just three weapons "nearly 300 bullets were found in five cars attacked."