Mark Twitchell denied knowing murder victim Johnny Altinger, but when police found him with the dead man's car, prosecutors say the would-be screenwriter spun a story too fantastic to believe.

Twitchell is on trial in the first-degree murder of Altinger in a rented garage in October 2008.

Prosecutors allege that two weeks after Twitchell wrote and directed a movie about a man abducted and murdered, he followed the script for real and killed Altinger.

They also say they will enter into evidence a laptop diary, which they say graphically details the knifing and dismemberment of Altinger, and speaks of Twitchell's plan to become a serial killer.

It's alleged that Altinger was expecting to meet a woman he'd met on an Internet dating site when he drove his red Mazda 3 to the garage on Edmonton's south side.

He wasn't seen again. About two years later police fished his remains out of a sewer.

Days after the disappearance, Joss Hnatiuk, Twitchell's film buddy, got a call.

"Mark phoned me up to tell me about how he was at a gas station and met a guy who said he was moving to the Caribbean with his sugar momma and was going to sell his stuff off," Hnatiuk testified Thursday.

The seller was desperate, Twitchell told Hnatiuk, and sold him his red Mazda 3 for all the money in Twitchell's wallet -- $40.

"It sounds like one of those things too good to be true," Hnatiuk remembers telling Twitchell. "He thought so, too."

Hnatiuk said Twitchell couldn't drive a stick shift, so Hnatiuk agreed to pick up the car -- parked in the same south-side garage later labelled a crime scene -- and drive it to his house.

"He wanted to register it so he could sell it right away," Hnatiuk told the jury.

Court has already heard that the ground was already slipping out from beneath Twitchell's feet by the time he phoned Hnatiuk.

Altinger's friends had not seen him for days, since he told one of them he was going to the garage to meet a woman. But they did receive unusual emails in his name that said he had run off to Costa Rica for three months with a well-to-do woman named Jen.

Suspicious, they called police, and a day after Hnatiuk moved the car out of the garage, police were there talking to Twitchell.

Hnatiuk was now worried the car was stolen and all but demanded Twitchell report it to police.

He did. Within hours of his first police meeting, Twitchell told them about the car. He said it had slipped his mind in the first police interview.

Det. Brian Murphy said Twitchell told him the seller had a medium build and sported a Celtic knot tattoo on his neck.

Twitchell, said Murphy, relayed to him that the seller was persuasive. "He said the girl was very wealthy and taking him away on a vacation for three months and told him he should get rid of this car and when they get back she will buy him a new car," said Murphy.

Twitchell told another detective that the seller was, ironically, also named Mark and was "all about leaving in a hurry."

Crown prosecutor Lawrence Van Dyke suggested to the jury in his opening address that the story is unbelievably "absurd."

Court has heard that in the days that followed, police turned Twitchell's life upside down. They hauled in his film friends for questioning, searched the garage and walked through Twitchell's suburban home, which he shared with his wife and infant daughter.

Two weeks after Altinger disappeared, Twitchell was emailing friends urging them not to talk to police.

Cops can't be trusted, he told them. "Sometimes they do lie and make things up in order to get people to say things they otherwise would not," he said in the email.

A week later he was arrested. Police confiscated knives, saws and a cleaver they say were stained with Altinger's blood.

Family and friends say Twitchell was fascinated by Dexter Morgan, a fictional character in books and on TV who leads a secret double life as a vigilante serial killer.