Mark Twitchell

Early life and filmmaking career

Mark Twitchell was born and raised in Edmonton, Alberta, where he developed ambitions of becoming a filmmaker. He graduated from the Radio and Television Arts program at the Northern Alberta Institute of Technology in 2000. He married American Megan Casterella in January 2001, and they divorced in 2005. In January 2007, Twitchell married his second wife, Jess. The marriage ended following his arrest with divorce finalized in 2010. Through his company Xpress Entertainment, Twitchell pursued his cinematic dreams, most notably directing a full-length Star Wars fan film prequel titled Star Wars: Secrets of the Rebellion in 2007. The film featured a cameo by original trilogy actor Jeremy Bulloch and was set just before the events of A New Hope, though it remained in post-production and was never publicly released. He also wrote a script for a buddy comedy called Day Players and, in September 2008, shot a short horror film named House of Cards at a rented garage in south Edmonton. This garage would later become the central scene of his crimes.

The murder of Johnny Altinger

In October 2008, Twitchell began posing as a woman on the popular dating website Plenty of Fish. His intent was to lure men to the garage he rented, which he had prepared as a film studio and later as a murder scene. John Brian Altinger, a 38-year-old quality control inspector from White Rock, British Columbia, who was living and working in Edmonton at Argus Machine Co. Ltd., made contact with this fake profile. On October 10, Altinger informed friends he was going on a date and provided them the garage address. Upon his arrival, Twitchell attacked him, bludgeoning and stabbing him to death. Twitchell's subsequent attempts to dispose of the body were methodical and gruesome. After an unsuccessful attempt to burn the remains, he dismembered Altinger's body using a game processing kit, placed the pieces into garbage bags, and dumped them into a storm sewer near 130th Avenue and 87th Street in Edmonton.

To cover his tracks, Twitchell broke into Altinger's condominium and sent emails to the victim's friends, claiming Altinger had impulsively gone on an extended vacation to Costa Rica with his new romantic interest. He also sent a resignation email to Altinger's workplace but did not respond to a request for a forwarding address for Altinger's final paycheque. The ruse unravelled when Altinger's friends, finding his passport and other personal items still at home, grew suspicious and contacted police. The Edmonton Police Service launched a homicide investigation. When questioned, Twitchell provided an implausible story that Altinger had sold him his Mazda 6 car for 40 dollars before leaving the country. Police impounded Twitchell's car and laptop, finding Altinger's blood in the trunk of the vehicle. This evidence led to Twitchell's arrest on October 31, 2008, and a charge of first-degree murder.

Trial, evidence, and conviction

Twitchell's trial was dominated by a single piece of digital evidence recovered by police from his laptop. Despite having been deleted, forensic technicians retrieved a document titled "SKConfessions," which stood for "Serial Killer Confessions." The document opened with the line, "This story is based on true events," and proceeded to narrate in detail the planning and execution of a murder that closely matched the killing of Johnny Altinger. It described luring a victim via online dating, the setup of a plastic-sheeted kill room, the act of murder, and the subsequent dismemberment and disposal of the body. The Crown successfully argued this was a factual account of Twitchell's crimes and his stated desire to become a serial killer.

During the trial, Twitchell admitted to killing Altinger and authoring the document but claimed he acted in self-defence. He testified that the murder was a horrific accident stemming from a publicity hoax for his film project, where he intended to scare men who thought they were on a date so they would later come forward and generate buzz for his movie. He stated Altinger became enraged upon learning of the trick and attacked him first. The jury rejected this defence. The media extensively covered the trial, repeatedly noting Twitchell's fascination with the Showtime series Dexter and his identification with its protagonist, Dexter Morgan, leading to the widespread "Dexter Killer" moniker. On April 12, 2011, Mark Twitchell was convicted of the first-degree murder of Johnny Altinger. Justice Terry Clackson sentenced him to life imprisonment with no possibility of parole for 25 years.

The attempted murder charge and Gilles Tetreault

Prior to murdering Johnny Altinger, Twitchell had lured another man to the same garage. Gilles Tetreault, a computer company contractor, responded to a Plenty of Fish profile in early October 2008 expecting to meet a woman. Upon arrival, he was attacked by a man in a hockey mask wielding a stun baton. After a violent struggle, Tetreault managed to escape but, feeling embarrassed, did not report the incident to police until after news of Twitchell's arrest broke. Media outlets later dubbed him "The One Who Got Away." Following Twitchell's murder conviction, the Crown considered pursuing a separate charge of attempted murder against Twitchell for the attack on Tetreault. The prosecution argued the two incidents were part of the same criminal transaction, namely Twitchell's attempt to become a serial killer, and should be tried together. Justice Terry Clackson disagreed, ruling the offences were "related and connected, but remain discrete" and ordering the charges be severed.

On June 17, 2011, the attempted murder charge was formally stayed, meaning the Crown could resurrect it within one year. However, with Twitchell already serving a life sentence with maximum parole ineligibility, there was no practical benefit to proceeding, and the charge was eventually dropped entirely. Tetreault later published a personal account of his experience in the 2015 book The One Who Got Away. He has also given numerous media interviews about his ordeal, appearing on programs like Dateline NBC, 48 Hours Mystery, and The Fifth Estate.

Media coverage and public fascination

The Twitchell case generated intense media interest in Canada and internationally. Prior to the trial, extensive publication bans were imposed to protect Twitchell's right to a fair trial, which media organizations contested. Once the bans were lifted, a large press corps covered the proceedings, including American programs like Dateline NBC and 48 Hours. Following his conviction, Twitchell attempted to appeal on grounds that the media coverage had prejudiced the jury, but he abandoned this appeal in 2012. In December 2012, Dexter actor Michael C. Hall expressed horror that his character might have influenced real violence during a Canadian radio interview.

Post-trial, Twitchell's story has been featured in numerous true crime television programs and podcasts. It was the subject of Steve Lillebuen's 2012 book The Devil's Cinema and a 2017 episode of Crime Watch Daily that included an interview with Tetreault. In 2022, internet personality MrBallen covered the case on his podcast, and The Infographic Show produced a YouTube video about it. A film adaptation of Lillebuen's book was acquired by producer David Permut, with director Sam Hobkinson attached to the project.

Incarceration and parole board proceedings

Mark Twitchell is serving his life sentence at the medium-security Bowden Institution in central Alberta. In recent years, he has undergone psychological therapy and engaged with the parole system. He has applied for temporary escorted leaves, specifically requesting permission for escorted visits to see his parents in Edmonton. In its decision, the Parole Board of Canada acknowledged Twitchell was making behavioural progress and would be a manageable risk if released on temporary leave. However, the board denied his application, citing the potential psychological impact on the victims' families from him visiting the city where they reside. The panel noted it must remain cognizant of this impact despite his institutional progress.

During parole hearings, Twitchell has continued to downplay the influence of the Dexter television series on his crimes. He described his state of mind before the murder as an existential crisis involving a deteriorating self-worth. He maintained the narrative that the killing was related to a film project hoax gone wrong. The parole board noted that early in his incarceration, Twitchell displayed narcissistic tendencies and produced writings of a violent nature. In May 2013, it was reported Twitchell had purchased a television for his prison cell and had caught up on every Dexter episode he missed since his arrest.

Key documents and writings

Several writings by Mark Twitchell became central to understanding his motives and actions. The most critical was the "SKConfessions" document recovered from his laptop. This detailed narrative outlined the planning and execution of a murder that matched the Altinger killing, stating its purpose was to document the author's "progression into becoming a serial killer." Another document found on his computer, titled "A Profile of a Psychopath," was believed by investigators to be a self-analysis written by Twitchell, though it was not entered as evidence for the jury. Following his conviction, Twitchell engaged in extensive correspondence with author Steve Lillebuen.

• SKConfessions: A detailed first-person account of planning a murder, setting up a kill room, and disposing of a body, recovered from Twitchell's laptop.
• A Profile of a Psychopath: A self-analytical document found on Twitchell's computer, detailing personality and behaviour traits.
• Prison correspondence: An estimated 350 pages of letters written to author Steve Lillebuen between 2010 and 2013.
• Fake emails: Messages sent from Johnny Altinger's email account claiming he was on vacation in Costa Rica.
• Online dating profiles: Fake female personas created on Plenty of Fish to lure potential victims.

Works based on the case

The shocking nature of the Twitchell case has inspired several non-fiction books, media projects, and planned adaptations. Journalist Steve Lillebuen wrote the 2012 true crime account The Devil's Cinema with Twitchell's cooperation. Gilles Tetreault, the intended victim who escaped, published his personal account The One Who Got Away in 2015. A film adaptation of The Devil's Cinema was acquired by producer David Permut, with Sam Hobkinson set to direct. The case has also been covered by programs like Dateline NBC and the podcast Strange, Dark and Mysterious.

• The Devil's Cinema (2012) by Steve Lillebuen. A comprehensive true crime account of the case and trial, written with the cooperation of Twitchell.
• The One Who Got Away (2015) by Gilles Tetreault. A first-person memoir by Twitchell's first intended victim, detailing his attack and escape.
• Film adaptation: The film rights to The Devil's Cinema were acquired by producer David Permut, with Sam Hobkinson set to direct.
• Television coverage: The case has been featured on Dateline NBC, 48 Hours Mystery, CBC's The Fifth Estate, Biography Channel's I Survived..., and Investigation Discovery's Dates from Hell.
• Podcasts: Covered in episodes including MrBallen's "Strange, Dark and Mysterious" podcast (April 2022) and the Canadian True Crime podcast.
• Online video: The Infographic Show published a YouTube video detailing Twitchell's life and crimes.

Questions about Mark Twitchell

Why was Mark Twitchell called the Dexter Killer?

Mark Twitchell earned the media nickname "the Dexter Killer" because his murder of Johnny Altinger closely mirrored methods depicted in the television series Dexter. During his trial, his interest in the series and his personal identification with its lead character, vigilante serial killer Dexter Morgan, were noted repeatedly. He staged a garage with plastic sheeting as a kill room and meticulously dismembered his victim. A document recovered from his laptop, entitled "SKConfessions", began by stating it was the story of his progression into becoming a serial killer. This combination of actions and stated inspiration led several media outlets to refer to him by that nickname.

What was the SKConfessions document?

The SKConfessions document was a critical piece of evidence in Twitchell's trial, recovered from his laptop after being deleted. The title stood for "Serial Killer Confessions. It was a first-person narrative that began by stating it was based on true events and detailed the author's progression into becoming a serial killer. The document described planning a murder, luring a victim through a fake online dating profile, setting up a plastic-sheeted kill room, and the process of killing, dismembering, and disposing of a body.

Who was Gilles Tetreault?

Gilles Tetreault was a computer company contractor who became Twitchell's first intended victim in early October 2008. Lured by a fake female profile on Plenty of Fish, Tetreault went to Twitchell's garage expecting a date. He was attacked by a man in a hockey mask with a stun baton but managed to fight off his assailant and escape. Embarrassed, he did not report the attack to police until after Twitchell's arrest for murder. Media outlets later nicknamed him "The One Who Got Away."

What was Twitchell's defence at trial?

At his trial, Mark Twitchell admitted to killing Johnny Altinger but claimed he acted in self-defence during a botched publicity stunt. He testified that his plan was to lure men to his garage under false pretences, attack them as part of a hoax, and then let them escape to generate buzz for his film. Twitchell claimed Altinger became violently angry upon learning of the trick and attacked him first. The jury rejected this explanation, finding the premeditated nature of the crime proved first-degree murder.

Has there been a movie made about Mark Twitchell?

As of now, a major film about the case is in development but has not been released. The film rights to Steve Lillebuen's 2012 book The Devil's Cinema were acquired by film producer David Permut. Director Sam Hobkinson is attached to direct the adaptation. The story has been covered extensively in true crime television documentaries, including episodes of Dateline NBC, 48 Hours, and CBC's The Fifth Estate.

Where is Mark Twitchell now?

Mark Twitchell is currently incarcerated at the medium security Bowden Institution in central Alberta. He is serving a life sentence for the first degree murder of Johnny Altinger, with no possibility of parole for 25 years. Recent parole board decisions have denied his applications for temporary escorted leaves to visit his parents in Edmonton. The board acknowledged his progress but denied the leave, noting the possible psychological impacts on the victims' families.

Sources and further reading

• Mark Twitchell (Wikipedia)
• Leave bid denied for Edmonton murderer Mark Twitchell ... (globalnews.ca)
• The Murder of Johnny Altinger (“Dexter Murder”) (canadiantruecrime.ca)
• Inside the mind of Mark Twitchell, "The Dexter Killer" (cbsnews.com)
• Leave bid denied for Edmonton man convicted in notorious ... (calgary.citynews.ca)

Checked by the Nosy Mag desk. Last updated 2026-10-19.