THE CANADIAN PRESS

WASHINGTON – Human rights groups are incensed about a startling revelation this week that one of Canadian Omar Khadr's chief interrogators was a U.S. soldier involved in the horrific case of an Afghan prisoner who was tortured to death.

Sgt. Joshua Claus's name came out in a Guantanamo Bay courtroom on Thursday, a slip by the judge in Khadr's case that fuelled defence assertions he may have been coerced during interrogation sessions after his July 2002 capture in Afghanistan.

Fifteen soldiers from two different U.S. army units, including Claus, would later be charged after two prisoners died that December.

One was a young taxi driver, thought by most of the Americans to be innocent of terrorism, who was beaten so severely he couldn't bend his legs any more before he died.

Claus pleaded guilty in September 2005 to maltreatment and assault of the man, known only as Dilawar, at the Bagram airfield detention centre outside Kabul. He was sentenced to five months in jail.

"With each new revelation, it becomes increasingly clear why the United States insists on prosecuting these cases in a system that permits convictions on the basis of evidence extracted through coercion and abuse," said Ben Wizner, a staff attorney with the American Civil Liberties Union who attended Khadr's hearing.

"Torture is at the very centre of these prosecutions. Unless these trials are moved to a system with traditional due process protections, we face the shameful possibility that Khadr and others will be convicted with statements that were literally beaten out of them."

Claus's involvement with Khadr is doubly troubling, said defence lawyer Lt.-Cmdr. William Kuebler, because the Canadian was just 15 years old and severely wounded in the firefight in which a U.S. Special Forces soldier was killed.

Khadr, facing a charge of murdering Sgt. Christopher Speer, was shot twice in the back and had shrapnel embedded all over his arms and legs.

On Friday, Col. Peter Brownback, the military judge presiding over a hearing in Guantanamo Bay, gave Khadr's lawyers a lot of the ammunition they need to defend him in an upcoming trial.

Brownback gave them permission to interview a military commander who allegedly altered a report to blame Khadr for Speer's death. The judge also granted Kuebler's request for the names of all of Khadr's interrogators and the notes of their sessions.

The defence believes Claus was there for nearly all of them.

Khadr's three months in Bagram before he was sent to the U.S. prison camp in Cuba is the "critical period," said Kuebler.

His statements during that time shouldn't be admissible in court if he was abused, the defence lawyer said.

"His principal interrogator was somebody we know was involved in detainee abuse," Kuebler told reporters. "I think that creates an overwhelming lack of confidence in the government's evidence."

A deputy chief prosecutor for the Guantanamo trials, Army Col. Bruce Pagel, said it was too early to assess whether any evidence had been tainted by abuse at Bagram.

Kuebler has been unable to obtain access to Pentagon investigations into the mistreatment of detainees there.

But the Pentagon report on the deaths of Dilawar and another detainee named Habibullah – first obtained by the New York Times in 2005 – is a terrible indictment of how at least some of them were handled.

Dilawar died when his heart stopped as a result of "blunt force injuries to the lower extremities," according to his autopsy report. He had been chained by his wrists to the top of his cell for days.

Claus, a specialist with the 519th Battalion, was one of his final interrogators.

The 2,000-page confidential army file on the case quotes another soldier saying that on the day Dilawar died, Claus stood behind him and twisted up the back of the hood that covered his head.

"I had the impression that Josh was actually holding the detainee upright by pulling on the hood," he said.

"I was furious at this point because I had seen Josh tighten the hood of another detainee the week before. This behaviour seemed completely gratuitous and unrelated to intelligence collection."

At his 2005 court-martial, Claus admitted he forced water down Dilawar's throat and said he constantly felt pressure to gather information quickly.

By the time of Dilawar's final interrogations, most of the Americans involved thought the father of a two-year-old simply happened to be driving his cab past the U.S. base at the wrong time.

The report outlined repeated incidents of abuse that went far beyond the two deaths, including guards striking shackled detainees with impunity.

Brownback has scheduled another hearing in Khadr's case for May 13, pushing back the trial that was supposed to begin earlier in the month.

His rulings Friday represented a big coup for the defence, which has long chaffed at what it calls a secretive, unfair process that doesn't follow the rules of law.

Kuebler will now be able to interview the military commander known only as "Col. W," whose report on the day of the July 2002 firefight reportedly said the assailant who threw the grenade that killed Speer had also been killed.

That would rule out Khadr as a suspect.

The report was revised months later under the same date, Kuebler alleges, to say a U.S. fighter had only "engaged" the assailant.

The prosecution has denied any tampering.