Edmonton police officers who used Tasers to subdue a knife-wielding man who was high on methamphetamine during an arrest in 2015 acted properly, according to an ASIRT investigation.

The man died as a result of excited delirium syndrome brought on by the drugs in his bloodstream, ASIRT executive director Susan Hughson said in a news release Monday.

Hughson said the half-dozen officers who responded to a chaotic emergency call at the man's home in December 2015 used reasonable and proportionate force during the arrest.

"Indeed, the resort to less-than-lethal force should be commended," Hughson wrote in her report about the investigation. "At the time, the man constituted a threat of death or grievous bodily harm to any person present."

Officers had dealt with man before

Police first encountered the 49-year-old in October 2015, when a family member called police to say the man was at an Edmonton casino and was either high on drugs or having a mental breakdown.

Officers who responded said the man appeared paranoid and delusional. It took four officers to restrain and handcuff the man, who was arrested under the Mental Health Act. He was taken to hospital, seen by medical personnel, and released back into police custody the same day. He was charged with assaulting a police officer and an EMS attendant.

"A psychological assessment after this incident identified an unspecified psychosis, possibly linked to substance abuse," Hughson said in the news release.

Two months later, on Dec. 7, the man came home from work and over a five-hour period "voiced paranoid and delusional thoughts and engaged in erratic behaviours," Hughson wrote. "The delusions centred on his spouse, his neighbours, satanic cults and a possible intruder."

A teenager was the only other person home that evening.

Shortly after 11 p.m., the man armed himself with a large kitchen knife.

"He indicated he was scared for his life and searched his teenage child based on a belief that the child might have a gun," Hughson wrote.

At 11:22 p.m., the man called 911. Soon afterward a neighbour also called 911 to report people yelling inside the man's home.

Man was holding knife when police arrived

One officer en route to the call recognized the man's name, checked police records and confirmed he had dealt with the same man at the casino six weeks earlier, Hughson said.

Three police cars arrived at 11:54 p.m. Officers heard yelling and screaming inside. One officer banged on the front door. No one answered. Another officer at the back door had a clear view of the man through a glass door. The man was seen pacing back and forth. He held a large knife in his right hand.

One officer at the back door drew his sidearm and another pulled out a Taser. One officer shouted at the man to drop the knife. The man's movements were described as "frantic and aggressive."

"He brought the knife to his throat," Hughson wrote. "He appeared agitated, distraught, and confused."

Officers at the front door finally smashed out the glass and unlocked it. One officer stepped inside and ordered the man  to drop the knife. He did not respond.

The teenager, on the floor nearby, told officers the man was high on drugs, and repeatedly asked them not to shoot but to use their Tasers instead.

'Overt suicidal motions'

Hughson said the officers thought the teenager was in danger. They finally got the teen out of the room. Three officers deployed their Tasers "repeatedly" but couldn't incapacitate the man. They couldn't get close enough to disarm him. The man made "overt suicidal motions" by trying to slash his neck with the knife, Hughson wrote.

The slashes drew blood.

One officer moved in closer and fired a Taser, incapacitating the man. He dropped the knife and fell to the floor on his back. He was immediately put in handcuffs.

The man was conscious and breathing. He let out a loud scream and kicked his legs violently. Police put him in leg restraints. He continued to struggle.

"Within approximately two minutes and 55 seconds, the man went into medical distress," Hughson wrote. "The restraints were immediately removed and CPR was commenced."

An ambulance was staged a short distance away. The man was transported to hospital where he was pronounced dead.

'Incoherent, irrational and agitated'

During an autopsy, the medical examiner determined that the use of Tasers did not cause or contribute to the man's death.

"It is the opinion of the [medical examiner] that the man died as a result of excited delirium syndrome that was due to methamphetamine toxicity; struggle during police restraint was considered a significant contributory condition."

"The man appeared incoherent, irrational and agitated," Hughson wrote. "He was holding a large knife in a manner consistent with its use as a weapon to cause harm. It is my opinion the officers had a duty to act.

"The officers also attempted to resolve the situation and control and restrain the man as quickly and safely possible, with a view to achieving a positive outcome without additional significant injury to anybody, including the man."

The Alberta Serious Incident Response Team has a mandate to investigate incidents involving Alberta police that result in serious injury or death.