GATINEAU, Que. — One month after he shot an unarmed Taliban insurgent, Capt. Robert Semrau risked his life to treat Afghan soldiers wounded during a deadly mortar attack in the Panjwaii District, his court martial heard Monday.

Pte. Joseph Villeneuve said Semrau saved his life during the mortar bombardment of an embattled Afghan National Army outpost in Mushan.

Identifying the telltale sound of an incoming mortar, Semrau told Villeneuve to pull a wounded Afghan soldier behind a nearby Ford Ranger truck. The mortar round landed a moment later where the soldiers had been standing.

"He saved my life right there," Villeneuve told Semrau's sentencing hearing.

Semrau then ran outside to assist other wounded Afghan soldiers, despite the continuing mortar fire.

"He was completely calm, level-headed, telling us what to do," Villeneuve said of Semrau. One Afghan soldier was killed and six were injured in the bombardment.

Semrau was the senior Canadian officer on scene at the time of the attack.

"He was always about the troops, making sure the troops were safe," Villeneuve said, adding later: "From my experience, he's a great leader and a great man."

That assessment was largely shared by two officers with whom Semrau worked during his five-year career in the Canadian military. They painted him Monday as a courageous and dedicated soldier.

Both Maj. Cayle Oberwarth, who fought alongside Semrau in Afghanistan, and Lt.-Col. Kevin Cameron, commanding officer of the 3rd Battalion of the Royal Canadian Regiment to which Semrau is attached, said they would be willing to serve with him again should the judge return him to service.

But the senior most ranks of the Canadian Forces do not want Semrau to remain in uniform.

Brig.-Gen. Denis Thompson, commander of Task Force Kandahar at the time that Semrau shot the severely wounded insurgent, said a message must be sent to soldiers and the public that such conduct is "completely unacceptable."

"It's such a blow to the credibility of the institution that I don't think we have any other option but to relieve him from service," Thompson told the judge, Lt.-Col. Jean-Guy Perron, who must decide Semrau's punishment.

Called as a prosecution witness, Thompson said he was speaking for the Canadian Forces chain of command.

As a self-policed institution, Thompson said, it's critical for the military to maintain its credibility when dealing with cases of individual wrongdoing.

Semrau's conduct, he said, undermined the Canadian-led counter-insurgency campaign in Kandahar, which depends upon winning the consent of the local population through "the legitimate application of force."

If Canadian soldiers disobey the rules of armed conflict, they compromise that effort, Thompson said.

All soldiers, he noted, are duty-bound to treat wounded combatants after the fight has been won.

It is not up to a soldier on the battlefield to deem someone beyond help. In fact, he said, only a combatant who has been decapitated or reduced to a skeleton can be declared dead by a soldier on the battlefield.

Semrau, 36, has been convicted of disgraceful conduct for the battlefield shooting in Helmand province. Evidence at his three-month trial suggested the Oct. 19, 2008 incident was a mercy killing.

He faces up to five years in jail, but the judge also has a range of lesser options, including dismissal, a reduction in rank or reprimand.

Lawyers for the prosecution and defence are to outline Tuesday the punishments they believe Semrau should face.

Oberwarth told court he was with Semrau as Canadian and Afghan forces were dismantling a combat post in the village of Zangabad, about 10 kilometres east of Mushan, in November, 2008 when the post came under mortar attack.

Semrau, he said, ran to his convoy to relay information to assist a Canadian counter-attack even though mortars continued to land.

"Captain Semrau's actions, to my mind, showed a high degree of physical courage," Oberwarth said.

During cross-examination, the officer conceded that Semrau defied the laws of armed conflict and the Geneva Conventions by shooting a wounded combatant. Nonetheless, Oberwarth said, Semrau has proven he can lead soldiers under fire.

"He's a good man with a good heart who I'd be willing to serve next to," he told the court martial.