A serving US Army officer who told a court he agreed with President Barack Obama that the Guantanamo Bay prison camps should be closed down has been removed from a jury hearing allegations of war crimes against a former child soldier.

Prosecutors claimed the unnamed lieutenant colonel had "pre-conceived" views that might harm their case. But the exclusion of the officer, who had been called to sit as a juror in the controversial military commission trial of Omar Khadr at the US naval base in Cuba, has only added to the perception of prejudice.

Mr Khadr is accused of killing a US soldier with a grenade and helping to make IEDs to be used against American forces when he was 15 years old in Afghanistan. Among the seven jurors remaining on the panel are officers who have lost close friends or colleagues fighting in Iraq and Afghan-istan. One had a friend killed in the 11 September attacks on the Pentagon. A female officer who was cleared to serve on the trial jury told the court she was awarded the Purple Heart for bravery after being wounded leading her soldiers into a firefight with Iraqi or al-Qa'ida militants in which two subordinates were killed.

It also emerged that many of the officers had volunteered to take part in the proceedings. During questioning of the 15 potential panellists all but one told the court they either believed Guantanamo Bay should stay open or did not hold an opinion on the subject. None of them thought the US had used torture to extract confessions.

In this context the lieutenant colonel, who said he agreed with his Commander-in-Chief on the policy of Guantanamo and torture, presented a lone voice of international consensus.

During the jury selection process, the army officer – who described himself as a military academic who also taught soldiers — was asked by prosecutor Jeff Groharing as to whether he had any views about Guantanamo.

He replied: "I agree with the President the detention facility should be closed down." He said that it "eroded America's reputation in the world," and that after speaking to Europeans and academics he backed the views of the former UN Secretary-General Kofi Annan and the former Attorney General of the UK, Lord Goldsmith QC, who had both condemned the detention of prisoners at Guantanamo.

He said he thought that some earlier policies had lost America its "reputation for being a beacon of freedom."

Asked specifically which policies had led him to this conclusion he authoritatively cited examples including; charge without trial, torture, rendition and the denial of access to members of the International Committee of the Red Cross to detainees held in secret locations. He went on to say that he believed a small number of detainees may have been killed while in American custody but added: "I don't think my views differ from those of the President."

By the time he had admitted that he would be "suspicious" of any evidence obtained under torture his fate was sealed. Throughout the whole process Mr Khadr looked on impassively from his seat next to his legal team close to the jury box. Defence lawyers acting for Mr Khadr claim he was subjected to torture before making statements to US interrogators.

The army officer's views were virtually identical to those articulated by Mr Obama during the presidential campaign in 2008, when he called Guantanamo, "a sad chapter in American history". When he signed an executive order to shut the facility down last year, the President said he was doing so "to restore the standards of due process and the core constitutional values that have made this country great."

But when chief prosecutor Jeff Groharing later had an opportunity to exclude members of the jury pool, he used his one exclusion permitted under military commission rules to keep the army officer off the jury panel. "It's clear he has a lot of opinions," Mr Groharing said. "I think he has preconceived ideas that detainees were mistreated."

Mr Khadr, a 23-year-old Canadian citizen whose father was a trusted associate of Osama bin Laden, claims he was treated inhumanely and threatened with rape while in US military custody, causing him to give a confession that he has since retracted.