EDMONTON - Five years have passed since four unsuspecting Mounties on a stakeout were cut down by a cop-hating troublemaker near Mayerthorpe, Alta.

The force and even those close to the officers who died concede that an upcoming fatality inquiry -- the one remaining avenue for a public airing of the facts -- is unlikely to fill in all the gaps in what led to the worst massacre of RCMP officers in modern history.

The biggest question: how did James Roszko pull it off?

A trial last year of two men who helped drive Roszko around the night of March 3, 2005, revealed how he was seething at police, who were watching over a marijuana grow operation and chop shop they had found in a Quonset hut on his farm. But the narrative ended with an armed Roszko being dropped off at the edge of the property.

Eight hours later, shots rang out and constables Brock Myrol, 29; Anthony Gordon, 28; Leo Johnston, 32; and Peter Schiemann, 25, lay dead. Roszko took his own life, and along with it, any chance the story would be told in full.

"There will be few aspects of Mayerthorpe that will ever be viewed as being final or definitive," says Cpl. Wayne Oakes, the police spokesman on this case since Day 1.

"Even at the outcome of the highest level of inquiry or findings or court process, there will still be areas that some will have questions or doubt about."

There's a sadness in Colleen Myrol's voice as she reflects on how quickly the five years have passed. She says she realizes that some key details surrounding her son's death will never be known.

"I really do believe there will always be a mystery around the whole event," she says. "We know more of the story now than we did before, and that does help that we've solved some of those issues.

"They're not nagging for me. I don't try and give it much thought."

Rev. Don Schiemann, Peter Schiemann's father, says no one will ever know all the details of what happened in the hours after Roszko was dropped off.

"I don't think we should consume ourselves with that which we can't ever know," Schiemann says. "Why waste our time with that? Let's just learn from what we do know."

The question of where Roszko hid the semi-automatic weapon he used "remains a huge unknown," says Oakes.

Last year, after an elaborate RCMP sting investigation, the two men who gave Roszko a ride and a second rifle that night took a plea deal. Shawn Hennessey and Dennis Cheeseman got 15 and 12 years in prison, respectively, for manslaughter, but are appealling their sentences.

Police analysis of the crime scene revealed that Roszko hid under a sheet as he snaked across a snow-covered and bush-dotted field toward the Quonset, where he slipped inside and waited for the Mounties.

Some blame RCMP commanders for not being more aggressive in securing Roszko's property since they knew he hated police. He had a record of violence and threats, but the Mounties chose not to deploy a tactical unit. And why were junior officers assigned to the stakeout?

Oakes bristles at questions about RCMP tactics.

"If there had been emergency response team personnel there, they would not have been in the same (state of readiness) as when they first entered that Quonset," he says. "They wouldn't have been in that state of heightened tactical alertness ... because they had been there for many hours.

"Nothing untoward, nothing sinister, nothing threatening. As far as they knew, the property was cleared and a safe place to be."

Schiemann says there is already plenty of evidence to suggest that the relative inexperience of the constables on the stakeout was not a factor in the deadly outcome.

"Anybody on that site was fair game for Roszko. As a matter of fact, the other two officers that weren't killed, that didn't go into the Quonset hut, had many, many years of experience, and had they gone in they would have been victims as well."

Author Robert Knuckle wrote "The Mayerthorpe Story: From Ambush to Aftermath" and interviewed veteran officers involved in the case.

He believes the Mounties didn't send an emergency response unit because it was too expensive. He also believes the relative inexperience of the constables at the stakeout simply reflects the way things are in policing.

"On cold, lonely night surveillance like that, invariably it's the junior people that get the assignment," Knuckle said from his home in Dundas, Ont. "You certainly couldn't call for an emergency response team. That's thousands of dollars worth of overtime."

Knuckle, who was recently made an honorary RCMP veteran, says the big question is where Roszko hid the assault rifle that he used and why didn't police take more precautions when they had intelligence that suggested he had the weapon.

"The word got back to the Mounties that this guy had this assault rifle -- it's absolutely illegal in Canada -- and they went out there on two occasions and searched and couldn't find it, so where the heck was that thing?"

The final review of the Mayerthorpe massacre may still be months away. The appeals of Cheeseman and Hennessey have to be heard first. Alberta requires a fatality inquiry in all police shootings, but not until after all criminal proceedings are exhausted. Such reviews cannot find blame, but can offer recommendations on how things could be improved.

Oakes says RCMP have not found any major errors in their review of the murders.

"The fatality inquiry may find certain conclusions, but at this point in time, based on the information that I have, it does not appear ... that anything of a significant flaw or error was done."

The shooting's fifth anniversary will be marked with a simple candle-lighting ceremony Wednesday evening at a park in Mayerthorpe where memorial statues pay tribute to the four Mounties. The RCMP are playing it low key and few, if any, family members will attend.

But organizer Shila Thibault says people have been flocking to the memorial site since it was put up.

"They don't hesitate to let the tears fall, to hug the person next to them," says Thibault. "There's an aura of dignity and honour and remembrance and hope for the future. And I still feel it and I go there almost every day."