Neighbours in Lake Bevan Place phoned police about an injured man asking for help and trying forcibly to enter a home. (CBC)

Cocaine, not a stun gun, killed a southern Alberta man involved in a struggle with RCMP officers, a medical examiner has concluded.

Grant William Prentice, 40, a resident of the small city of Brooks, southeast of Calgary, died on May 6 in the local hospital after a police officer stunned him with a Taser, a device designed to incapacitate people with an electric shock.

No charges will be laid against the two RCMP officers involved, said the Alberta Serious Incident Response Team (ASIRT), which looks into deaths and serious complaints in the province involving police officers.

An autopsy by a medical examiner found that Prentice had more than double the amount of cocaine in his body than is normally considered life-threatening.

Prentice died of acute cocaine toxicity and the Taser did not play a role in his death, said ASIRT executive director Clifton Purvis on Wednesday morning.

Prentice was prodded by a Taser twice in the "push stun" mode, Purvis said.

"Pain compliance provides a very localized pain that is not meant to incapacitate you," Purvis said. "Indeed, it is just pain in that one localized area. There is no current that goes through the body if you use it in the 'push stun' mode."

Prentice was known to the Mounties as a drug addict, RCMP spokesman Peter Hourihan said, adding the man's death is a tragedy.

"I just want to say first and foremost that this is a very tragic situation and we would like to express our heartfelt condolences and sorrow to the family of Mr. Prentice," he said. "He was a son, a father and a loved one."

Struggle in a cul-de-sac

Police were called to a residential cul-de-sac, Lake Bevan Place, in Brooks at 7:30 p.m. on May 6.

Neighbours had phoned police about an injured man asking for help and trying forcibly to enter a home.

"Two officers arrived at the scene and tried to take the man into custody. A struggle ensued and one officer attempted to subdue the male with his conducted energy device," ASIRT said at the time. "Two more RCMP officers arrived and the man was eventually handcuffed."

An ambulance crew assessed Prentice and took him to the Brooks hospital, where he died at 8:30 p.m.

ASIRT said Prentice was "known" to police. According to court records, Prentice was charged with causing a disturbance in 2001 and fined.

Following the May incident, Alberta NDP Leader Brian Mason called on the province to ban Taser use because he believes the devices are not safe and are being improperly used by police.