A senior Canadian commando who choked and "almost killed" a subordinate in an apparently unprovoked attack in Afghanistan was never tried in court, despite a confession.

CBC News has obtained exclusive details of the little-known 2005 assault showing the warrant officer responsible for the attack admitted to the principal facts.

There were five witnesses to the attack, three of whom pulled the warrant officer off his victim during the altercation at a forward operating base in Afghanistan. But even with those witnesses in hand, the military never put the soldier on trial.

Instead, the case was subject to a series of court battles between different groups of defence department lawyers, and the man at the centre of those fights never set foot before a judge.

The case calls into serious question the willingness of the Canadian military to pursue charges against its secret and elite special forces troops.

It also comes at a time that the Canadian Forces are wrapping up a four-year investigation of the command and control of Canada's special forces.

That inquiry was prompted by insider allegations of murder, reckless bombardment, battlefield executions and allied war crimes. Those allegations were first reported by CBC News and were subject to years of investigation by military police, who nicknamed the file "Sand Trap."

No charges were ever laid.

CBC News has learned the top-secret work of that board of inquiry is complete, but military lawyers are currently vetting its report.

The new allegation of serious wrongdoing in Afghanistan could lend credibility to the suggestion Canadian commandos are not as well controlled as they should be.

Eyewitnesses described attack

The warrant officer in this case was a senior member of Canada's top-tier special operations regiment, Joint Task Force 2. His victim was a subordinate, a master corporal who apparently talked back when asked to help set up some targets for a firing range.

Documents obtained by CBC News show the attack happened on Aug. 10, 2005, at a forward operating base in Kandahar province, where the Canadian commandos had just been deployed.

'[The warrant officer] jumped down from a trailer he was working on and ran to the master corporal and strangled him from behind.'—Military documents

Details are contained in part of a letter written by the JTF2 commander at the time, Lt-Col. Mike Day, who was later appointed commander of all Canada's special operations forces.

The letter from Day, who is now a major-general, says that "after a dispute with one of his subordinates, the [warrant officer] assaulted the latter by strangling him."

Day wrote that the choking attack carried on for about 45 seconds.

"It took the robust physical intervention of three other members of JTF2 before the [warrant officer] finally freed his subordinate."

Day's letter was written to explain his decision to send the warrant officer back to Canada to face an investigation and potentially a court martial.

In his letter, Day described details of the attack that were related to him by witnesses and those who intervened.

"[The warrant officer] acted in a fit of rage … after a verbal exchange between the master corporal and him about how to do a task (preparing targets for a firing exercise)."

The warrant officer had apparently been transporting targets to the range area when he asked the master corporal for help.

"He jumped down from a trailer he was working on and ran to the master corporal and strangled him from behind," military documents say.

"[The warrant officer] admitted the principal facts, but mentioned he had done so in self-defence."

"[He] didn't demonstrate any remorse, but, to the contrary, he maintained that he was justified."

Rank demanded full court martial

As a senior soldier, the warrant officer was employed in a leadership role in JTF2, likely as the second-in-command of a troop of highly trained special operations assaulters.

According to the documents, Day sent the senior soldier home to be investigated and tried because his senior warrant officer's rank demanded a full court martial, rather than a summary trial conducted on the ground in Afghanistan with officers on hand.

• Joint Task Force 2: Canada's elite fighters

The warrant officer was later charged with mistreating a subordinate and aggravated assault.

The allegations in Day's letter have not been tested in court — because the military never did bring the case to trial.

That's because it felt it was unable to bring charges against the warrant officer without exposing his name and membership in a semi-secret unit to public scrutiny.

Military security rules require all soldiers — even lawyers — to keep secret the names of members of JTF2.

But, in Canada, all courts — even military courts — are presumptively open to the public.

The issue of openess became the subject of a legal fight between the director of military prosecutions and the chief military judge of the Canadian Forces.

Deciding that issue took until December 2006, when a Federal Court judge dismissed a request from the director of military prosecutions that would have compelled the chief military judge to assign a judge to the court martial of the JTF2 member. The chief military judge had declined to appoint a judge in the case because the charge sheet was classified as secret.

By then it had been 16 months since the attack on the master corporal in Afghanistan.

In the meantime, the warrant officer had already been administratively relieved of his command and sent off to work in another unit on so-called extra-regimental employment.

He complained about that and made a series of other administrative grievances to an independent board. It's in documents from that board that the details of the attack in Afghanistan are laid out.

'Big boy rules'

They show that just two days after the attack the warrant officer voluntarily wrote a declaration in which he furnished his version of the facts.

He later wrote about his conduct that he "refused to participate in a leadership popularity contest and adopt the TV-style approach demanded by his subordinates," and that he applied "the big boy rules."

Members of the Canadian Forces JTF2 rappel from a helicopter off the shores of Churchill, Man., in August. (Adrian Wyld/Canadian Press)

The latter is a special forces phrase that suggests elite commandos do what they feel they need to do, and don't wait or expect to be managed or watched over like privates in the regular army. But the phrase is also freighted with the suggestion a soldier who plays by those rules doesn't need to be disciplined when he makes an error.

The documents say the warrant officer "believes he acted preventatively, in self-defence, although he admits he took the first shot."

They say five witnesses to the attack all indicated the warrant officer "had completely lost control of his conduct," and continued to choke his subordinate even when the master corporal was trying to cry "uncle" by slapping the ground.

The grievance board concluded it was an "explosive situation" that, left unchecked, would have put the commando troops' broader mission in Afghanistan in peril.

Despite the shocking and violent nature of the attack and the written confessions in hand, military prosecutors chose to keep arguing legal points with other military lawyers, instead of trying to find a way put him on trial by court martial.

Instead, the director of military prosecutions chose to appeal the 2006 Federal Court decision and argue its secrecy point before the Federal Court of Appeal.

That decision came down in December 2007, two years and four months after the attack happened.

According to the Defence Department, the court concluded that allowing the charge to be sealed for as long it takes a military judge to hear a request for confidentiality would not offend the open court principle.

Documents show that two months later, in February, military prosecutors finally and successfully laid criminal charges against the warrant officer. For some reason, three months after that, prosecutors withdrew them.

Military prosecutors withdrew the charges in 2008 because they "no longer had a reasonable prospect of conviction," according to Melanie Villeneuve, a spokeswoman with National Defence.

It's hard to imagine how that could be true, given the warrant officer's written admissions and the presence of five witnesses.

"As a result of this incident, the chain of command at JTF2 lost confidence in the individual and he was removed from employment with the unit and has not served with JTF2 again," Villeneuve said.

That leaves a senior soldier, supposedly an elite commando, who attacked and "almost killed" a subordinate at a forward operating base in Afghanistan, unpunished by law.