The Canadian military says it will investigate the suicides of three veterans from the war in Afghanistan in less than one week.

The latest to take his life is Warrant Officer Michael McNeil, whose body was found at CFB Petawawa on Wednesday.

Earlier this week, Master Corporal William Elliott died at his home near CFB Shilo in southwestern Manitoba and Master Bombardier Travis Halmrast died in a Lethbridge, Alta., hospital after a suicide attempt in a jail.

The military will undertake boards of inquiry into each death — routine procedures that look at the circumstances and systemic issues that may have led to a particular incident.

"Our thoughts and prayers are with the families, friends and colleagues of these departed individuals, and I wish all those associated with those individuals peace during this difficult time," defence minister, Rob Nicholson, said on Thursday.

Conservatives note treatment, counselling

Earlier in the day, Nicholson called the deaths "very troubling," but noted since 2011, the Conservative government has poured millions of extra dollars into the treatment and counselling of returning soldiers.

Lt.-Gen. Marquis Hainse, commander of Canadian Army

Lt.-Gen. Marquis Hainse, commander of the Canadian Army, released a statement on Thursday saying "the loss of a soldier ... is tragic and we mourn with the family and friends of the deceased while the Canadian Army endeavours to support them in their loss." (Canadian Forces)

The commander of the Canadian Army was equally upset.

"I am disturbed by the loss of three of our soldiers," said Lt.-Gen. Marquis Hainse.

Hainse said the military wants to see if there are lessons to be learned to prevent future suicides.

NDP wants to know cause of suicides

NDP defence critic Jack Harris is skeptical, saying he's not confident the military is finding out what's causing suicides in the ranks. Harris said the three suicides show the Harper government is failing wounded soldiers.

"We have had soldiers who've stood up for Canada when we asked them to do that. We should be standing up for them and I don't think we're doing that," he said.

Figures released by National Defence last summer reported that 22 full-time members took their own lives in 2011. The numbers for 2012 have not been made public.

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Cpl. Stuart Langridge killed himself after tours in Bosnia and Afghanistan left him with post-traumatic stress disorder, which sparked an inquiry.

Some have questioned the data because the figures apply only to regular force members, excluding reservists whose part-time designation means they fall under the jurisdiction of civilian agencies in their home provinces.

Harris added there have been 50 military inquiries into military suicides since 2008 that are incomplete.

National Defence was asked on Thursday how many investigations were still outstanding, but no one was immediately available to comment.

Military boards of inquiry are often held behind closed doors and the families of suicide victims do not have automatic access to the findings and recommendations, said an expert in military law.