Aspiring Edmonton filmmaker Mark Twitchell plotted the killing of Johnny Altinger "to become a serial killer" and the jury has little choice but to convict him of first-degree murder, Crown prosecutor Avril Inglis said in her closing argument on Monday.

Altinger's death was no accident and no act of self-defence as Twitchell testified last week, she told the jury.

Twitchell, 31, admitted to using an online dating site to lure Altinger, 38, to a rented garage in south Edmonton  in October 2008, and stabbing him in self-defence. Twitchell said he dismembered the body and dumped the remains in a north Edmonton sewer.

'He planned to lure Mr. Altinger with the sole purpose of killing him.' —Crown prosecutor Avril Inglis

"The plan was to become a serial killer and nothing else," Inglis said. "The plan was to lure, to incapacitate, to restrain, to extort and then to murder his victims. 

"He planned to lure Mr. Altinger with the sole purpose of killing him."

All the evidence points to a carefully planned murder, Inglis said, evidence including SKconfessions, a 42-page document the Crown maintains is Twitchell's diary and confession.

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Johnny Altinger is shown in an undated photo. (CBC)

The document describes a murder in circumstances similar in almost every detail to Altinger's death.

Inglis told jurors any information they received solely from Twitchell, a proven liar, should carry no weight.

"This was not a plan for a movie, a book or an urban legend. The simplest explanation is the correct explanation," she said.

"The truth is obvious and it has been proven beyond a reasonable doubt."

Twitchell not guilty, says lawyer

Earlier Monday, Twitchell's lawyer told the jury it must be absolutely certain that his client is guilty.

"You might be suspicious about his conduct and what happened in that garage in 2008," said Charles Davison in his closing argument. "You might even think events unfolded as in what’s been referred to as the SK document.

"Even if you think it probably happened the way it happened in that document, that’s not proof beyond a reasonable doubt."

'Things have been written up for the purpose of making a better story.' —Twitchell lawyer Charles Davison

Much will come down to whether jurors believe that SKconfessions is a diary or a fictionalized version of certain real events, Davison said.

There are enough differences that the jury must see the document was not intended to be a completely accurate and truthful account of things that happened, he said.

"Things have been written up for the purpose of making a better story."

Story is intended to shock: lawyer

The story was supposed to be the character’s progression into becoming a serial killer and intended to shock the reader, he said. 

That's how Altinger's death went from one of self-defence as described by Twitchell, to a thrill kill as laid out in the document, said Davison.

Davison suggested the killing and disposal of Altinger was too inept to be a carefully planned murder.  

He pointed to Twitchell renting the garage in his own name.

"Does that make sense if he’s going to commit a planned, thought-out intentional murder?"

"There will be only one conclusion you can reach," Davison summed up. "You simply cannot be sure of what happened the night of Oct. 10 in that garage.

"The only proper verdict to return is one of not guilty."

The judge will instruct the jury Tuesday morning.

With files from CBC's Janice Johnston