Aspiring filmmaker Mark Twitchell has been found guilty of first-degree murder and sentenced to life in prison for bludgeoning, stabbing and dismembering a stranger.

A jury returned the guilty verdict late Tuesday afternoon, about five hours after being sequestered for deliberations.

Twitchell, 31, used an online dating site to lure Altinger, 38, to a rented garage in south Edmonton on Oct. 10, 2008, before killing him.

Twitchell then dismembered the body and dumped the remains in a north Edmonton sewer.

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Johnny Altinger is shown in an undated photo. Altinger was bludgeoned and stabbed to death in a south Edmonton garage on Oct. 10, 2008. (CBC)

He showed no reaction as the verdict was read, although a gasp was heard in the courtroom.

Altinger's mother, Elfriede, began to cry.

She said in her victim-impact statement that she can’t allow herself to think about the pain and horror her son must have endured.

She wrote that she doesn’t wish the death penalty on Twitchell, but that she wants him to reflect on what he’d done and "die a slow death every day of his life."

Justice Terry Clackson thanked the jury and offered counselling services to those who felt they needed it.

"It has been a very difficult case, even for some of us who have been in this business for a long time," said Clackson. "You have been stoic."

Jury did not see document

Through the trial the jury heard 18 days of testimony and saw 111 exhibits.

'I’ve always had a dark side I’ve had to sugarcoat for the world.'

—A Profile of a Psychopath

But the jury was not shown one document discovered on Twitchell's laptop. The seven-page essay, called A Profile of a Psychopath, had been deleted.

In it the author, believed by investigators to be Twitchell, analyzes his own personality and behaviour. The author admitted while he doesn't fit perfectly the description of a psychopath, he is a pathological liar.

"I habitually lied my entire life," he wrote. "Despite my incredibly well adjusted and healthy family life and upbringing, it never stopped.

"I always apologized but never meant it and never corrected the behaviour."

'Distinct lack of empathy'

The author also claimed he has never felt empathy.

"For as long as I can remember I have always had a distinct lack of empathy, I've always had a dark side I've had to sugarcoat for the world."

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Mark Twitchell shown during an interview with the CBC in 2007. (CBC)

He went on to write, "On my journey of discovering my disorder, I've discovered my killer instinct.

"I've often fantasized about killing people who have wronged me or threatened to hurt me or my family in the future, but that's where it ends."

Actually carrying out a murder, he said, doesn't make sense.

"I don't feel that taking someone else's life is worth the loss of my freedom or the amount of time, energy or expense one needs to put in, in order to conduct such acts."

The other major consideration is his work, he said.

"I can direct my dark energies into my film work."

"As a producer I can profit from the sale and distribution of my work. But as a serial killer I would get nothing more than a quick rush of adrenalin and a prison sentence to follow."

Never hurt animals

But in other ways the author does not fit the profile of a serial killer, he said.

"I do not con or prey on my family members or friends. I never hurt animals as a child either."

But he admits to cheating regularly on his wife, who he describes as "an excellent mother to our child, and the greatest partner that anyone could ever ask for."

"I still cheat, but only for the thrill of it," he said.

He once tried to be totally honest with his wife, he said.

"I had a conversation with my wife one night where we fully explored my lack of empathy," he said. "She asked me a variety of probing questions. Every answer I gave her, although truthful this time, were deeply disappointing to her. No after no when she was looking for yes after yes."

Automatic life sentence

Twitchell's fondness for the Dexter television show was well-documented during the trial, and he had a Facebook profile under the name of protagonist Dexter Morgan, a vigilante serial killer.

Twitchell had claimed he lured Altinger to the garage to create online buzz for a short film about a Dexter-like killer, which he produced in the garage two weeks earlier and was calling House of Cards

He testified when Altinger became angry at being made a fool and attacked him, he beat and stabbed him in self-defence.

Twitchell has been sentenced to life in prison with no chance to apply for parole for 25 years.

With files from CBC's Janice Johnston and Briar Stewart