GATINEAU, Que. - Canadian Forces Capt. Robert Semrau's conduct in the minutes after a fierce battle in Afghanistan was disgraceful, but it wasn't murder, a military panel ruled Monday.

The unprecedented court martial found Semrau not guilty of second-degree or attempted murder for the shooting of an Afghan insurgent in October 2008, but guilty of a lesser charge of disgraceful conduct under the National Defence Act.

While one expert hailed the decision as the right choice for the panel to make, it was cold comfort to Semrau's family, who had been buoyed by an outpouring of public support since the father of two was charged with the crime last year.

"As a family, we're disappointed in the verdict," said Semrau's brother, Bill, outside the military tribunal room. "We've always believed my brother did nothing wrong."

Semrau was also found not guilty of a lesser charge of negligent performance of a military duty.

The decision marks the first time a soldier has been convicted of shooting a combatant, said prosecutor Lt.-Col. Mario Levaille.

But it also speaks to how difficult it is to prove crimes committed in the fog of war.

The prosecution called a dozen witnesses during the four month trial, which also travelled to Afghanistan to hear witnesses there.

Semrau himself never testified.

The body of the insurgent he was charged with killing was never recovered, making forensic evidence of murder impossible to find.

"We proved the fact that he shot and wounded an unarmed man, that's what we proved beyond a reasonable doubt," Leaville said outside court.

"Why they reached the verdict they reached, I cannot say."

The dramatic legal-military saga began on Oct. 19, 2008, on a dusty battlefield in the Taliban-infested Helmand province, just west of Kandahar, the province where most of Canada's soldiers are stationed.

Semrau was part of a team of Canadian soldiers assigned to the Afghanistan National Army as mentors.

Following an intense fire fight that pitted Canadian and Afghan forces against the Taliban, an insurgent lay on the verge of death.

He had been strafed by a U.S. helicopter gunship and witnesses described devastating injuries, including a severed leg and a gaping hole in his abdomen.

The trial was told that Semrau fired two rounds from his rifle into the dying man and that he'd told fellow officers after the shooting that he simply wanted to put a wounded and dying enemy fighter out of his misery.

But the concept of a mercy killing is so far removed from acceptable military practice that the verdict against Semrau can serve a valuable lesson, suggested retired Col. Michel Drapeau, who is now a lawyer.

"Justice will be seen to render soldiers a service," he said.

"If this issue of mercy killing is in fact common currency among soldiers, this just put an end to it. It puts an end in a very brutal and certain way that this is illegal, immoral, unethical and will not be tolerated."

But may also have soldiers thinking twice about firing their weapons at all, Drapeau said.

"There is a grey zone there, when an enemy is down, he could be down legitimately, because he's injured, because he's sick or because he wants to surrender," he said.

"But he could also assume a prone position with the intent of calling you."

Semrau's conviction carries with it a maximum penalty of five years in prison. He could also be discharged from the military.

Semrau is a married father of two girls and had a spotless record with the British and Canadian militaries.

Lawyers for both sides were scheduled to meet again on Tuesday for a Charter of Rights argument over the military's sentencing procedures.