VANCOUVER -- A Vancouver police officer who was involved in a fatal shooting that was captured on a cellphone video won't face charges because he could reasonably argue self-defence, a special prosecutor announced Monday.

Paul Boyd was shot multiple times after police responded to a 911 call about a disturbance in August 2007. He was bipolar and was not taking his medication at the time.

Various investigations and reviews by police and Crown prosecutors had cleared Const. Lee Chipperfield, but the case was placed under renewed scrutiny last year when a cellphone video emerged in the media.

Chipperfield had told a coroner's inquest he believed Boyd was armed with a bicycle chain when he fired the fatal shot. He also said he believed Boyd may have been wearing body armour because it appeared as though he wasn't affected by the initial shots.

But the shaky video showed Boyd crawling along the ground, no longer holding the chain, in the seconds before the ninth and final shot.

An outside agency was brought in from Alberta to conduct yet another review of the case and a special prosecutor was appointed to review the evidence.

The B.C. Criminal Justice Branch released a seven-page statement Monday explaining special prosecutor Mark Jette's decision to not charge the officer.

"If Const. Chipperfield was prosecuted for an offence alleging culpable homicide, a reasonable doubt on the issue of self-defence would require an acquittal," the statement said.

"The evidence made available to the special prosecutor in this case was that Const. Chipperfield personally believed resort to lethal force was necessary to preserve himself and others from death or grievous bodily harm."

Police were called to a report about an assault at a bus stop, though Monday's statement notes the call turned out to be inaccurate.

At first, Boyd was co-operative, according to the prosecutor's statement, dropping a hammer when police officers asked him to. However, when the officers attempted to handcuff Boyd, the situation deteriorated and Boyd swung the bike chain, hitting one of the officers.

During the confrontation, Chipperfield fired nine shots, eight of which struck Boyd.

Midway through the gunfire, the video shows Boyd had dropped the bike chain and another officer pushed it aside, the prosecutor's statement says. That officer later said he had told Chipperfield to "hold your fire," though Chipperfield and other officers at the scene said they didn't hear it.

The prosecutor's statement said the video does not tell the whole story about what happened that night.

The video starts after six shots had already been fired and doesn't show the confrontation that prompted the shooting, the statement says. The entire incident lasted less than three minutes.

While Boyd is seen on the video crawling on the ground, he moves behind a car, blocking the camera's view, before the final shot. An autopsy concluded the angle of the fatal shot indicated Boyd may have been either on his hands and knees or leaning forward while on his feet.

As for Chipperfield's belief that Boyd was still armed when the fatal shot was fired, the statement notes other civilian witnesses had the same, albeit inaccurate, recollection.

"A number of the civilian witnesses who viewed the incident involving Mr. Boyd also failed to observe a police officer remove the chain and padlock prior to the fatal shot," said the statement.

"The special prosecutor concluded that Const. Chipperfield's evidence that he failed to note Mr. Boyd being disarmed may reflect the fact that sometimes people do not see what is there to be seen."

Vancouver police Chief Jim Chu said in a statement the case was "difficult and sad for everyone involved."

"As I have said from the beginning of this tragic incident, I would like to once again extend our sincere regrets and condolences to the Boyd family for their loss," Chu said in the statement.

"No police officer ever comes to work with the intent of taking a life."