Born in Edmonton, Alberta, Twitchell was an aspiring filmmaker who dreamed of making blockbuster movies. In September 2008, he shot a short horror film at a garage he rented in the south end of Edmonton.
John Brian "Johnny" Altinger was a 38-year-old male who worked as an oilfield equipment manufacturer at the time of his disappearance. On October 10, 2008, Altinger informed his friends that he was going to meet a woman he had been chatting with on the online dating website PlentyofFish. His friends soon became concerned when they received strange emails from Altinger, explaining that he had met a woman who was taking him on a long vacation to Costa Rica. Altinger's boss received a resignation letter by email, but never got a response to his request for a forwarding address for Altinger's final paycheque.
After growing more and more suspicious, several of Altinger's friends broke into his condo only to find his passport, dirty dishes and no indication anything had been packed. A homicide investigation was soon launched by the Edmonton Police Service.
Twitchell was arrested on October 31, 2008, and charged with the first degree murder of Altinger on the same day.
The key piece of evidence presented by the Crown at Twitchell's first degree murder trial was a document, entitled "SKConfessions" where the SK stood for Serial killer, which was recovered from Twitchell's laptop despite being deleted. The document begins with the passage:
"This story is based on true events. The names and events were altered slightly to protect the guilty. This is the story of my progression into becoming a serial killer."
It goes on to describe in detail the author's extensive planning, failed first attempt, and successful second attempt at murdering a man by luring him to his garage using fake online dating profiles. It also describes the process of dismembering the victim's body and his numerous attempts to dispose of the remains. During his trial, Twitchell admitted to killing Altinger and authoring the document. However, he contended that he acted in self-defense and that much of the document was a fictionalization of the events. He claimed that the mindset of the narrator, which portrayed the killing as deliberate and intentional, was sensationalized in an attempt to make a more compelling novel.
Twitchell, convicted of first degree murder in the online luring death of Johnny Altinger, still faced an attempted murder charge for his alleged attack on Gilles Tetreault. Tetreault testified that he was lured off the website PlentyofFish expecting a date with a woman, only to be attacked by a man in a mask with a stun baton when he arrived at a garage rented by Twitchell. He was able to escape with his life. Crown prosecutors had not immediately decided if they would pursue the charge of attempted murder upon securing a conviction of first degree murder since a conviction of attempted murder would not add to the life sentence Twitchell had already received.
On June 17, 2011, an attempted murder charge against Twitchell was stayed in the Court of Queen’s Bench of Alberta. Crown prosecutors were given one year to resurrect the charge.
The attempted murder charge against Twitchell was finally dropped. The decision to drop the second charge may seem odd to those who have followed the case closely. Detectives were adamant they had gathered a mountain of evidence – much of it revealed during the murder trial – while even Twitchell himself admitted on the witness stand to committing the attack. In preparing the case for trial, the Crown had argued in court for both the attempted murder and first-degree murder charges to be heard simultaneously as they were part of the same “transaction” of allegedly becoming a serial killer. Under Canadian law, charges can only be heard together if they are strongly linked in some way. Court of Queen’s Bench Justice Terry Clackson was not convinced by the prosecution’s argument that the attack on the first victim, Gilles Tetreault, and the murder of Johnny Altinger were part of the same transaction. He ordered the charges to be severed and heard separately. “The offences are related and connected, but remain discrete,” Justice Clackson wrote in his reasons for the decision. “As a result, the attempted murder charge cannot stand on the same indictment as the charge of murder because they are different transactions.” A conviction of first-degree murder in April 2011 secured a maximum sentence — life in prison with no parole eligibility for 25 years — and therefore virtually eliminated any need to proceed with more charges.
Extensive media coverage of the case created debate both inside and outside of the courtroom with observers arguing in favour and against the media reporting on "sensational" details of the crime.
Prior to the criminal trial taking place, Crown prosecutors and the defense also sought vast publication bans and sealing orders over the police evidence, preventing the media from reporting on the details of the case until the jury would hear it during the future trial. The media fought the application, but the judge eventually agreed to both a sealing order and publication ban, stating in his ruling that "there is a real risk that pretrial publicity will undermine the accused's constitutionally protected right to a fair trial." The jury pool was then polled through a "challenge for cause" procedure to determine if a potential juror had been influenced by extensive media coverage prior to the publication bans taking effect.
When the bans were lifted, a substantial media presence attended and reported on the trial, including American television programs Dateline NBC and 48 Hours.
After his first degree murder conviction, Twitchell used the extensive media coverage of his case as grounds for an appeal. He argued in his notice of appeal that "the media attention surrounding my case was so extensive, so blatant and so overtly sensationalized that it is unreasonable to expect any unsequestered jury to have remained uninfluenced by it, regardless of judges' instructions in the charge." However, he then abandoned his appeal in 2012.
In December 2012, Michael C. Hall, who plays Dexter Morgan on Dexter, was interviewed by Jian Ghomeshi on the Canadian radio show Q. Hall said he does not think Dexter supports the lifestyle of serial killers. "I would hope that people's appreciation was more than some sort of fetishization with the kill scenes," he said. Ghomeshi brought up Twitchell and Hall said, "I wouldn't stop making Dexter because someone was fascinated by it only in that way. I try to tell myself that their fixated nature would have done it one way or the other, but it seems that Dexter had something to do with it. It's horrifying."
In May 2013, it was reported that Twitchell purchased a television for his prison cell. He stated that he has seen every Dexter episode that he missed since he was arrested and convicted of first degree murder.
Twitchell's case was featured on the American newsmagazine Crime Watch Daily on May 1, 2017. Much of that day's program focused on Twitchell's methods and featured interviews with Gilles Tetrault, his first intended victim, and Steve Lillebuen, writer of the book The Devil's Cinema which focused on case. Part of the report included a return trip by Tetrault to the garage where the incidents took place.The Devil's Cinema, a non-fiction book about Twitchell's case and trial, was written by Steve Lillebuen and published in March 2012.
The One Who Got Away, a personal account from the original intended target of convicted murderer Mark Twitchell, was written by Gilles Tetreault and published in October 2015.