Ross Soukonnik shown in an undated photo.

A retired Edmonton police officer, fired as a 911 call evaluator after failing to act on a call from a woman murdered hours later, has filed a union grievance over his dismissal, CBC News has learned.

Two years ago, Maia Soukonnik, 60, called 911, complaining her son had assaulted her, when the call ended suddenly. 

The call evaluator, former constable Dale Moore, did not call back or send police to the house.

Three hours later, the woman's son Rostislav (Ross) Soukonnik, 22, called 911, saying his mother was dead.

"In this particular occasion, it turns out it's a very tragic result, one we're all very, very sad to see," said Sgt. Tony Simioni, head of the Edmonton Police Association, the labour organization that represents police.

"Was it negligence to the point where he needed to be fired? Or maybe just educated?"

Soukonnik, 22, was later found not criminally responsible for stabbing his mother to death, after two psychiatrists found he was suffering from schizophrenia at the time and could not understand the consequences of what he was doing.

Police kept the 911 mistake quiet, but disciplined Moore quickly.

"Well, the particular individual is no longer on staff, and as a matter of fact hasn't worked a shift since that particular evening," said Insp. Brian Lobay. "We do share the public's concerns and the service's concerns as to what happened."

Moore has since filed a grievance over his dismissal, said Simioni. It is a first step through the police association aimed at getting Moore's job back.

"Nobody's happy with the result, obviously, and him more so than anyone," he said. "We all feel bad when this is the result of a mistake, or a miscalculation or a mis-evaluation by one of our members, whether they're retired or current.

"And even if can agree that it was an error, that it was a mistake, is it worthy of being fired?"

Moore could not be reached for comment.