A New Brunswick Mountie says he felt betrayed and sickened by RCMP Commissioner Bob Paulson's testimony in Moncton, N.B., last week about protecting the lives of officers.

''It was a complete disregard to the members, and an insult to the members who gave their lives, who put their lives in danger," said Cpl. Patrick Bouchard.

The RCMP has been on trial in Moncton, accused of failing to keep officers safe June 4, 2014, when a gunman killed three Mounties and wounded two others.

Testimony wrapped up last week, with Paulson as the defence's star witness.

Throughout the trial, officers who responded to the shootings testified high-powered carbine rifles — which were at the centre of the proceedings — would have helped take down heavily armed gunman Justin Bourque.

But Paulson quickly dismissed those thoughts during his testimony last Thursday, saying carbines would have made no difference that night.

Bouchard called that "a slap in the face."

During the trial, more than a dozen RCMP members approached CBC News to express frustrations with the force and its leadership. All wanted to remain anonymous, however, for fear of consequences.

Const. Douglas James Larche, 40, from Saint John, N.B., Const. Dave Joseph Ross, 32, from Victoriaville, Que., and Const. Fabrice Georges Gevaudan, 45, from Boulogne-Billancourt, France, left to right, were killed in Moncton, N.B., on June 4, 2014. (RCMP)

Bouchard, who was a friend of fallen officers Fabrice Gevaudan, Dave Ross and Doug Larche, and lent a hand the night of the shootings, said he has suffered a lot of pent-up anger and grief.

After Paulson's testimony, he just couldn't hold it in anymore, he said.

Bouchard sent a letter to Paulson, who is retiring from the force at the end of the month after almost 40 years of service, including five as the top Mountie.

The corporal shared the letter on his Facebook page and on a private page for RCMP members.

His anger is evident in the first line: ''Sir, And I'm using sir because of your title and because I have to. Not because I want to.''

RCMP Commissioner Bob Paulson, centre, heads from the Moncton Law Courts with defence lawyers Ian Carter and Jeff Doody during a break last Thursday. (Andrew Vaughan/Canadian Press)

He continues: ''Sir, the burden of command comes at a price. I hold you personally responsible for the deaths of my friends. I hold you responsible because you as a manager (you are not a leader) have placed money and image ahead of the safety of the members you are sworn to protect.''

Throughout the trial, court heard that RCMP senior management placed a high importance on public image, which drove the need for extensive research to justify patrol carbines for frontline officers, before the military-style weapons could be adopted.

One witness, RCMP Supt. Bruce Stuart, even admitted public perception took precedence over officer safety.

When asked by the Crown last week why he wanted to testify, Paulson said it was because as the commissioner, he was accountable for his members.

But when prosecutor Paul Adams asked him if he was then ready to accept responsibility for the death of three officers, Paulson replied "no."

Bouchard said he felt almost physically ill when he heard Paulson's statement. He calls it "a tough pill to swallow."

I feel shame that my leader chose to risk my life and the life of my friends. I hope you find peace in your new job. I know I won't. - Patrick Bouchard, RCMP corporal

For the first time in his career, Bouchard wrote, he looks at his uniform and feels shame.

"It's the uniform that you chose not to wear in court. The uniform that connects you to the membership of the RCMP. The uniform that connects you to me. The uniform that connects me to my fellow members. I feel shame.

"I feel shame that my leader chose to risk my life and the life of my friends. I hope you find peace in your new job. I know I won't.''

Bouchard said he has not heard back from Paulson since writing the letter.

Cpl. Patrick Bouchard speaks out about RCMP Commissioner Bob Paulson's testimony in Moncton. 1:07

The RCMP declined to comment to CBC News because the force's alleged violations of the labour code are still before the court.

But Bouchard's letter has generated strong reactions on social media. Bouchard said he's received hundreds of calls and messages from current and former RCMP members.

"Most of them are saying 'this is exactly how I felt' or 'you didn't say enough,'" Bouchard said. "You can tell that members are emotional. It hits them to the core."

Bouchard said he recognizes there may be repercussions for speaking out, but he hopes the force sees this as a cry for help from its members instead.