EDMONTON James Roszko was a ticking bomb primed with a murderous lust for revenge long before he shot and killed four RCMP officers on a lonely Alberta acreage, says a forensic psychologist.

"He was so revenge-oriented and he had for so many years been fantasizing about killing a police officer, that it was like the last straw, the next penny to drop, somebody is going to pay," said forensic psychologist Matt Logan, a retired RCMP investigator who put together a picture of Roszko's psychological state after his shocking murder-suicide on his Mayerthorpe property on March 3, 2005.

"His fantasy was well formed. His revenge orientation was well ingrained. I can't say specifically that he was in a hunting mode, but he was certainly ready to do that act, should the opportunity arise."

In the days after the mass murder, Logan was called in to determine why Roszko, a man with a long history of conflict and violence, had decided to kill police officers on that particular day. He went through Roszko's personal papers and conducted interviews.

"It was to get a picture inside this person's head of why did he take those boys at that time in that fashion . . . It's a jigsaw puzzle of the mindset."

Roszko shot down constables Peter Schiemann, Leo Johnston, Brock Myrol and Anthony Gordon, before turning the gun on himself.

Most such killers carefully select the individual they want to kill but to Roszko the individual wasn't important, as long as the target was an RCMP officer, Logan said.

"His fantasy was directed specifically to the RCMP. His fantasy was killing a police officer," he said.

Any small episode, such as an RCMP officer pulling him over at the side of the road, could have inspired Roszko to kill, Logan says.

Logan says he can't yet divulge all he knows about Roszko because a fatality inquiry into the Mayerthorpe massacre has yet to be held. The inquiry will not go ahead until all criminal proceedings in the case are over, says RCMP spokesman Cpl. Wayne Oakes.

Roszko's accomplices, Shawn Hennessey and Dennis Cheeseman, are appealing their murder pleas and their sentences.

There's some question as to when Roszko formed his intent to kill the officers guarding and searching his Quonset hut.

On the night of March 2, 2005, roughly 10 hours before the murders, Roszko pulled out a gun and ordered two young men from the nearby town of Barrhead, Hennessey and Cheeseman, to help him park his truck at Roszko's aunt's house, 38 kilometres from his own farm.

He then got Hennessey and Cheeseman to drive him back to his farm and to provide him with a rifle. Hennessey has said he had no idea Roszko, a highly secretive, even paranoid man, was going to kill any police officers. "There was no talk of Mounties, ever, from James Roszko to myself. Never. He wanted to go home and burn his dope," Hennessey has told the CBC.

Logan said he doesn't know if Roszko talked to Cheeseman and Hennessey about any plan to kill, but he strongly suspects that when Roszko demanded the ride and the weapon from Hennessey and Cheeseman, the killer was taking concrete steps to carry out his murderous fantasy.

"At some point from driving off the property to making arrangements to come back, the penny had dropped," Logan says. "He was in action at that point . . . There was a decision made.

"He wasn't going back to just see if anyone was on his property . . . I can't say that for positive, but that would be consistent with the psychopathic mind that I've dealt with for all these years.

"I don't think he had woken up that morning thinking, 'This is the day I'm going to take out a police officer.' I think it was just the affront of having people on his property."

Logan is writing a book, Charming the Snake, Policing the Psychopath, about how to best handle psychopaths. It will be out in 2010.