A report into the death of a Canadian soldier in Iraq, prepared by U.S.-led special forces, is now complete but won't be made public, the Department of National Defence says.

Instead, the findings are being fed into two Canadian military investigations looking at the circumstances behind Sergeant Andrew Doiron's death March 6 in northern Iraq. He was killed by Kurdish fighters in what the Canadian Armed Forces says was a "friendly fire" incident.

The military is so far resisting a more exhaustive probe of what befell Sgt. Doiron – a process known as a board of inquiry. The Forces convened such a board back in 2002 after another friendly fire incident where an American F-16 mistakenly bombed and killed four Canadian soldiers in Afghanistan.

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A board of inquiry is normally ordered if "a matter to be investigated is of unusual significance or complexity," according to Forces rules. It's an internal, non-judicial investigation of events that may affect the functioning of the Forces.

Defence Minister Jason Kenney said Canada is already in possession of the findings of the special forces report on the Doiron death. Chief of Defence Staff Tom Lawson "informed me this morning that he had received a summary of a U.S. report," the minister told the Commons on Monday.

The report, in the form of a "commander's inquiry" was conducted by Special Operations Joint Task Force Commander Iraq, the Department of National Defence said.

It's the only probe into Sgt. Doiron's death performed by soldiers not affiliated with Canada.

"This was a week-long investigation into the facts at issue," DND spokesman Daniel Le Bouthillier said.

The American-led review won't be released, though. "The information we have received thus far will be combined with what we learn from our investigations, and will inform our actions, and our lessons learned process, as we move forward," Mr. Le Bouthillier said.

The decision to keep the U.S.-led special forces report confidential raises further questions about the transparency of Canada's mission just days after The Globe's Mark MacKinnon reported he was blocked in his efforts to visit the site in northern Iraq despite having received approval from the Kurdish President and the Ministry of Peshmerga Affairs. Mr. MacKinnon had been seeking a clearer picture of the deadly incident in light of conflicting accounts about who was at fault – and was mysteriously informed the investigation was over.

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As many as 69 Canadian special forces soldiers are operating in northern Iraq as part of Canada's contribution to the fight against Islamic State militants. They are advising Kurdish peshmerga fighters.

Canada has restricted its scrutiny of Sgt. Doiron's death to a summary investigation conducted by Canadian special forces command and a separate review by Canadian military police who are trying to determine whether any wrongdoing took place. The Kurds are also investigating.

Mr. Kenney pledged in the Commons on Monday to release what he could from the two Canadian investigations, saying he'd make public "those aspects of these reports that do not bear on confidential military operations."

Liberal defence critic Joyce Murray said the government has to do better. "A thorough investigation should have been conducted during the past six weeks, and the results made public by now," Ms. Murray said. "It has become increasingly clear that a full board of inquiry may be the only way for Canadians to ever know what truly happened in this tragic incident."

The Department of National Defence hasn't yet ruled out a board of inquiry. The summary investigation taking place now "does not preclude the convening of a board of inquiry at a later date, should the chain of command determine that such a measure is necessary," the department said.

There was confusion Monday about whether the U.S.-led coalition fighting Islamic State in Iraq and Syria had in fact probed Sgt. Doiron's death as Ottawa had said weeks ago. A spokesman for Combined Joint Task Force Operation Inherent Resolve said the coalition "is not conducting a separate or concurrent investigation" but Canada's Department of National Defence later clarified it was the U.S.-led special forces command in Iraq that undertook a review.

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Mr. Kenney said he is still awaiting the reports from Canada's special forces or Canada's military police on the death.

Canadian military officials have said Sgt. Doiron and his fellow soldiers had prearranged their movements that night with the Kurds and had passed two other checkpoints without incident before the third post opened fire on them.