The release of Omar Khadr after 13 years of imprisonment has sparked huge interest in the case of the man known as "Guantanamo's child". Although I too was in Guantanamo, I never met him there. I only met a boy in Bagram whose severely wounded face, body, and mind had to endure the vengeance of a post 9/11 US military machine. Fifteen years ago, in the summer of 2002, that is the state in which I first encountered Omar Khadr.

I'd been detained by Pakistani Intelligence Services (ISI) in Islamabad, Pakistan, and questioned by the CIA before being flown off to the US military prison at Bagram airbase which was far more oppressive than Guantanamo.

Prisoners were dispersed between six communal cells housing around 10-12 each. The entrance to each cell had two caged metal doors - the "airlock" or "sally port" where prisoners were isolated - mostly for shackling purposes but also for seclusion from other prisoners, and punishment.

There were no windows, no natural light - just powerful floodlights shining down on us day and night. At the back of each cell an oil barrel cut in half served as a toilet.

Whispered conversations

The rules prohibited prisoners from talking to one another but most managed whispered conversations. Being one of a handful of English-speaking prisoners I often had conversations with the guards, one of which told me about a heavily wounded teenager they'd captured, who was accused of throwing grenades at unsuspecting US soldiers.

When Omar was brought to the cells next to me, it was clear that he was a young emaciated boy (he'd just turned 15) with shocking wounds all over his body. He was blind in one of his eyes and had deep exit wounds in his shoulder and chest. The stitching across the wounds reminded me of a corpse after autopsy.

At night, soldiers would isolate Omar in the airlock and scream at him calling him a murderer, a terrorist scumbag who deserved to die. But Omar was tranquil and never complained.

At night, soldiers would isolate Omar in the airlock and scream at him calling him a murderer, a terrorist scumbag who deserved to die.

Walking, talking, congregational prayer or reading the Quran aloud was an infraction of the rules. To punish us we'd be isolated in the "sally port", our heads hooded and our hands shackled to the top of the door for hours. This was hard enough for us able-bodied men but when it happened to Omar it broke our hearts.

But again, Omar was tranquil and never complained despite his horrific wounds. In fact, when he recited the Quran in his soft, gentle voice he appeared more serene.

Eventually Omar and I were moved to the same cell and we spent some time having muted conversations. A handful of soldiers, like Damien Corsetti "the Monster" - despite being accused of prisoner abuse - recognised Omar's mistreatment and afforded him some humane conduct.

'Buckshot Bob'

The guards dubbed Omar "Buckshot Bob" alluding to the primary cause of his injuries. The soldiers who captured Omar had shot him in the back with a shotgun - at point-blank range - even as he lay wounded in the rubble of the mud straw compound pulverised by US military bombardment where he was captured. Astonishingly, Omar survived. He was the only one.

Omar only stayed in Bagram for a few months and was sent to Guantanamo before me. I never saw him again but his story was always close by. After my release, I met with many of his civil and military attorneys and spoke to his family. He was the last citizen of a Western nation to be released.

We were all freed before him. His repatriation to Canada only came as a result of pleading guilty to "war crimes". Whatever he may have done, he certainly did not throw grenades at unsuspecting aid working soldiers.

Most of the prisoners who pleaded guilty in Guantanamo's kangaroo court-style military commissions process have gone home. That was Omar's ticket to repatriation where he could appeal the sentence and seek his freedom.

No bitterness

However, following his release Omar has challenged his Guantanamo guilty plea and maintains that there is serious doubt as to whether it was even possible that he could have thrown the grenade that killed the US Special Forces operative, with subsequent eyewitness testimony, from soldiers, supporting the suggestion that someone else threw the grenade.

Omar's words following his release on bail have overawed his supporters and silenced his critics. He neither complains nor is he bitter.

Omar Khadr is still not completely free: He has to remain at one address, wear an electronic tag, refrain from using a mobile phone or the internet and, crucially, is unable to see his family over 3,200km away, until he wins his appeal.

In Dennis Edney, he has more than just a lawyer; he has a committed friend who genuinely cares about him. But, like some of us, in the middle of the night, when all is quiet, Omar will crawl under his bed and cry, just as he did when his youthful wounded eyes watered the cells of Guantanamo and Bagram.

Moazzam Begg is a former Guantanamo Bay detainee and spokesman for Cageprisoners.

The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial policy.