Shocking bystander video depicting the final moments of Paul Boyd, a bipolar man who was gunned down by Vancouver police in 2007, has led authorities to reopen the case.

B.C. Police Complaints Commissioner Stan Lowe confirmed Tuesday that the video, which shows Boyd had dropped to his hands and knees moments before being shot in the head, will be independently reviewed by a police agency in Alberta.

"It is important that our office maintains a principled and measured approach in this matter," Lowe said in a statement. "I have personally viewed the video and support the decision to reopen the investigation of this tragic incident."

Clifton Purvis, director of the Alberta Serious Incident Response Team, has agreed to examine the footage and report back to authorities in B.C., Lowe said. The BC Coroners Service has also announced it will review its investigation and inquest into Boyd's death in light of the new video evidence.

Boyd was shot eight times in a span of 80 seconds on Aug. 13, 2007 by Const. Lee Chipperfield in the middle of Granville Street.

It appears the video, which was released Monday by the eyewitness who filmed it, begins with the seventh bullet being fired into Boyd's body.

The 39-year-old, who had moments earlier attacked officers with a bicycle chain, appears to drop his weapon and begins making guttural sounds. He then starts crawling on all fours towards a group of constables until a stopped car obscures the view.

Another shot, believed to be the one that pierced Boyd's face and killed him, is then fired off camera.

BC Civil Liberties Association executive director David Eby called the video "incredibly disturbing to watch," and said it affirms a number of troubling eyewitness accounts of the deadly confrontation.

Some witnesses recalled Boyd standing and continuing to threaten police when he was killed, but Eby said the recollection of those who remembered him unarmed and on all fours have proven more credible.

"The police complaint commissioner and the Criminal Justice Branch said ‘No, there's too much confusion for us to figure out what happened.' Well now there's a video, and we think it may well change their impression of what happened that evening."

‘I had already gone through that in my mind': father

Boyd's father Paul told CTV News that watching the video produced "very little emotional reaction" because he had already come to believe the version of events it depicts.

"It was a bit more visceral of course seeing it, but I had already gone through that in my mind."

He also said he's not holding his breath that it will for lead to real justice or accountability in his son's death.

"I never hope very much. I've seen what's happened over the past five years. The process drags out and it's forgotten … I've seen nothing come of it so far, and I frankly don't expect much to come of it now. I think the only difference now is the public may respond differently and realize what a travesty it was."

"Whether that makes any difference, I don't know."

The B.C. Criminal Justice Branch decided in 2009 not to lay charges against Chipperfield and in March, nearly five years after the incident, the police complaints commissioner ruled that he had not used excessive force.

Lowe acknowledged major discrepancies among witness accounts, but said at the time there was "no clear, convincing and cogent evidence" that warranted action against the officer.

Boyd, a professional animator, was manic and hadn't taken his medication the night he was killed, his psychiatrist told a 2010 coroner's inquest.

He was found kneeling on the ground at a bus stop with a hammer in hand by a group of four officers responding to 911 calls about a possible assault.

When one of the constables tried to handcuff him, Boyd struck him on the head with a bike chain, leaving a wound that would require stitches. He then hit another officer on the back with the weapon before running into the street.

The video of the resulting confrontation also appears to confirm the testimony of one constable who said he had time to run in and grab the chain from Boyd before the fatal shot was fired, something Chipperfield has testified he was not aware of.

There is an approximately 23-second gap between the two shots fired on the tape.

The coroner's inquest ended with the jury recommending that all officers be provided with intermediate weapons like bean-bag guns and Tasers to deal with distraught people.