VANCOUVER -- The fatal shooting of longtime homeless advocate Barry Shantz by a police officer will not be referred to Crown counsel for charges, B.C.'s police watchdog said in a report released Tuesday.

In its report, B.C.'s Independent Investigations Office wrote that the use of lethal force by a member of the Lytton RCMP, which occurred after a standoff that spanned over six hours on Jan. 13, "was necessary and proportionate to the risk."

According to the report, Shantz had a loaded shotgun in his hands and was suicidal, and before he walked out the front door of his Fraser Canyon home, told Mounties he wanted to be shot six times.

"There was nothing to suggest that (Shantz) was surrendering," the IIO's chief civilian director, Ron MacDonald, wrote in his report.

"It was not necessary to wait until he actually pointed the shotgun at someone or pulled the trigger – it would only have taken moments for him to do so," MacDonald wrote.

MacDonald said there were no reasonable grounds to believe any officer committed an offence.

"There were attempts to maintain the assistance of a trained mental health professional," MacDonald said at a news conference Tuesday.

"Unfortunately, in the time available, that didn't pan out."

Shantz's sister, Marilyn Farquhar, called the report "disappointing" and told CTV News she believes steps and opportunities were missed by the responding officers.

"They had helicopters there bringing in officers…but they didn't bring in a health professional," Farquhar said.

The IIO reviewed statements from 18 witnesses, including 11 police officers, along with recordings of 911 calls and police radio transmissions, ballistic reports, and autopsy and toxicology reports.

In its report, the IIO wrote crisis negotiators and family members had talked to Shantz during the standoff, and "he had remained adamant that he wanted to force a police officer to shoot him."

MacDonald told reporters police expended what he called "considerable efforts" to get Shantz to change his mind.

He called the shooting "different" than most other mental health calls because Shantz had fired a shot when the first officers had arrived at his home.

Farquhar called the report "shallow" and said it raised broader, systemic questions about how police respond to mental health emergencies, and the role of mental health experts

"If we can implement some change as a result of (his death), at least something positive came out of it," she said.

Farquhar said her brother, who had spent over a decade in prison in the U.S. for drug crimes, had long suffered from post-traumatic stress disorder (PTSD), something Shantz was open about.

"His partner called for help (that day), because (Shantz) was struggling," she said.

Farquhar described her older brother as a "very big person" who "was always pushing the limits."

Shantz was known as a lightning rod for his relentless advocacy for homeless rights in Abbotsford, where he lived before moving to Lytton.

Farquhar said her brother was both passionate and driven.

She's now creating a series of grief quilts that will share the stories of people Shantz met throughout his life, and the lasting impact he had on them.

The final one of three will be called "Hope."

"Even on his last day, he was advocating," she said. "So that's what (he) would have wanted (his legacy to be)."