Trevor Grimolfson, 38, died on Oct. 29, 2008. (CBC)Two Edmonton police officers who used a Taser in an altercation with an agitated man who later died will not face criminal charges, the civilian agency that investigates serious police incidents announced Wednesday.

"In my determination, their actions were justified when considering all of the circumstances," said Clifton Purvis, executive director of the Alberta Serious Incident Response Team (ASIRT).

"In this incident, I must defer to the office of the chief medical examiner and I conclude that in this incident, the use of the Taser did not cause or contribute to the death of Trevor Grimolfson."

Grimolfson, 38, a tattoo artist originally from Selkirk, Man., died in hospital after police responded to reports about a violent and agitated man in the area of Stony Plain Road and 153rd Street in west Edmonton on Oct. 29, 2008.

Although a Taser was used on Grimolfson three times during the arrest, the medical examiner found he died from "excited delirium" that was brought on by the amount of drugs he had taken.

According to Purvis, Grimolfson had taken a potentially lethal combination of ecstasy and ketamine, an animal tranquillizer better known by its street name of special K.

Grimolfson agitated on police arrival

When the police arrived at the scene, they found Grimolfson smashing articles at a pawn shop next door to the tattoo parlour. Officers could detect the strong scent of pepper spray in the air. Grimolfson had assaulted the 70-year-old owner of the store and his 30-year-old son, Purvis said, and bear spray had been used on Grimolfson in an unsuccessful attempt to subdue him.

Grimolfson was highly agitated, covered in blood, was breathing heavily and had clenched teeth, Purvis said.

The officers used the Taser on Grimolfson when he didn't obey a command to get on the ground and stop his rampage. Instead, the stun gun appeared to have no effect. Grimolfson continued moving towards the officers, prompting them to use the Taser a second time.

When that didn't work, they both tried to bring him to the ground and got him in handcuffs after a long struggle. That's when officers used the Taser a third time, this time in stun mode, Purvis said.

Grimolfson had been spitting, so officers had placed a spit mask on his face. The officers then noticed he was having problems breathing, Purvis said. Both the mask and the handcuffs were removed, and paramedics took Grimolfson to hospital, where he was pronounced dead.

During the 11-month investigation, 50 civilian witnesses were interviewed, including seven who witnessed the incident or portions of it, Purvis said. A number of police witnesses were also interviewed.