Killer Minds: Inside the Minds of Serial Killers & Murderers

Episode: MURDEROUS MINDS: The Dexter Killer Pt. 1

Release Date: September 15, 2025
Hosts: Vanessa Richardson (A), Dr. Tristin Engels (B)

Episode Overview

This episode embarks on a chilling and analytical exploration of "The Dexter Killer," Mark Twitchell—a failed Canadian filmmaker whose obsession with cinematic murder escalated into real-life violence. Hosts Vanessa Richardson and Dr. Tristin Engels blend narrative detail with forensic psychological analysis, examining how Mark’s lifelong detachment from reality, obsession with violent fiction, and increasing compartmentalization led to an attempted transformation into his own fictional killer. This is Part 1 of a two-part deep dive into the mind of a man who blurred art and atrocity, attempting to live out the twisted fantasies that once lived only in his scripts.

Key Discussion Points & Insights

1. Mark Twitchell’s Early Life & Fascination with Fantasy (04:15 – 08:52)

• Mark grew up in Edmonton, Canada, loving sci-fi, fantasy, and especially performing original and parody skits with childhood friend Kirk (e.g., “Judge Fred”—a mashup of Judge Dredd and Fred Flintstone).
• As a child, Mark’s imaginative play rapidly veered toward violent themes (“Wheel of Torture”), detailing scenarios where contestants met gruesome ends.
• Insight: Dr. Engels highlights the distinction between a healthy hobby and a dangerous obsession, noting Mark’s inability to achieve balance:

  “A hobby is typically something a child enjoys doing in their free time...A fixation or an obsession, on the other hand, goes far beyond that...It usually interferes with other important aspects of life like school or social activities.” (06:15 – 07:09)

2. Blurring the Line Between Fiction and Reality (07:38 – 08:52)

• Mark’s fantasies served as both refuge and source of power amid bullying and isolation.
• Dr. Engels warns this immersion can condition an individual to need escalating levels of violent fantasy for emotional release:

  “He is essentially, possibly conditioning himself that in order to get an emotional release or to feel powerful or even joy, he needs to do so through reenacting these violent thoughts.” (07:44 – 08:33)

3. Obsession with Anti-heroes and Escalating Online Behavior (08:52 – 12:26)

• Mark’s fixation grows as he immerses himself in Star Wars fandom, identifying most with Anakin/Darth Vader (defending even brutal acts on forums).
• He experiments with online deception—creating fake profiles as Satan, Jesus, or women flirting with men.
• Insight: Dr. Engels points to “online disinhibition”—empowering Mark to act without social consequence, giving him escalating thrills of control:

  “With Mark, this online behavior is actually a clear escalation. He’s gone from performing violence in skits...to psychologically taunting strangers online where he is actively causing harm.” (11:12 – 12:05)

4. Personal Setbacks and Intensification of Fantasies (12:26 – 17:46)

• Mark’s first marriage ends amid debt and claims of “extreme and repeated mental cruelty.”
• Returns to Edmonton and throws himself into fan filmmaking ("Star Secrets of the Rebellion"), achieving limited notoriety, even attracting minor “Star Wars” actors.
• Mark remarries, but soon becomes obsessed with the TV show “Dexter,” finding deep resonance with the double-life serial killer protagonist.

5. The Dexter Influence: From Fiction to Fixation (17:46 – 25:35)

• After bingeing “Dexter,” Mark’s filmmaking ambitions pivot to violent psychological thrillers. He conceives “House of Cards,” essentially a Dexter homage.
• He is increasingly unable to separate fantasy and reality, quitting his job against his wife’s wishes to focus on his film, all while hiding the truth.
• Analysis: Dr. Engels notes serious psychological fragmentation:

  “He’s compartmentalizing his life into different isolated parts, which can lead to a fragmented sense of identity...The more he detaches from reality, the more likely he is to become emotionally numb and desensitized to the consequences of his actions.” (20:06 – 21:10)

6. Filming “House of Cards” and Self-Identification with Killers (25:35 – 29:13)

• Mark meticulously recreates elements from “Dexter,” even obsessing over realistic kill scenes.
• He writes, “If my family and friends ever knew the real me, it would damage many of them, some irreparably.” (25:48)
• Dr. Engels explores Mark’s self-awareness and dangerous internal justification:

  “He knows on some level that his violent fantasies aren’t socially acceptable...He could be setting the stage for denial, believing that because others can’t handle the ‘real him,’ he is entitled to act out his violent fantasies without facing the consequences.” (25:59 – 27:00)

7. From Fantasy to Planning Real Murder (29:13 – 34:06)

• Dissatisfied with staged violence, Mark determines only the real experience will satisfy his need for “authenticity.”
• He starts crafting a real murder plan matching the script: creating a fake woman’s profile on PlentyOfFish, preparing a kill room, and writing a manifesto titled “SK Confessions”:

  “This is the story of my progression into becoming a serial killer.” (34:02)

8. First Attempted Murder: Gilles Tetreault (35:50 – 40:01)

• Mark lures Gilles to the garage. In a chaotic sequence, the victim escapes after a struggle, alerting neighbors; Mark deletes all evidence and experiences intense anxiety at nearly being caught.

• Dr. Engels draws a parallel to Jeffrey Dahmer’s failed first attempt, emphasizing how fantasy never accounts for messy real-life outcomes—failure only increases compulsion and determination to try again.

  “This just reinforced his urge to kill, because even though he failed, he still proved to himself he’s capable of carrying it out. Now all he has to do is refine his approach, which is something we see happen often with serial offenders.” (40:01 – 41:19)

9. Rapid Escalation: Selecting the Next Victim (41:41 – 43:56)

• The day after the attempt, Mark modifies his weapons and fake profile, repeating the scheme with a new target, John Brian Altinger.
• The episode ends on this dark note, setting up Part 2.

Notable Quotes & Memorable Moments

• On Mark’s Motivation:

  “If my family and friends ever knew the real me, it would damage many of them, some irreparably.”
  (Mark Twitchell's writings, 25:48)

• On Creative Desensitization:

  “Even though right now, no one’s being harmed, it’s still giving him a sense of joy or gratification…He’s essentially, possibly conditioning himself that in order to get an emotional release or to feel powerful or even joy, he needs to do so through reenacting these violent thoughts.”
  (Dr. Engels, 07:44 – 08:33)

• The Slippery Slope Between Hobby and Harm:

  “A hobby is typically something a child enjoys doing…A fixation or an obsession…goes far beyond that…interferes with other important aspects of life…It becomes problematic if it disrupts a child’s emotional development or well being.”
  (Dr. Engels, 06:15 – 07:09)

• Linking Art and Atrocity:

  “Mark romanticizing Dexter in this way, even writing a film inspired by him, is more evidence that he’s normalizing violent or antisocial behaviors.”
  (Dr. Engels, 25:59 – 26:40)

• On Escalating Compulsion:

  “Writing serves as an emotional release for him...By writing, he’s able to covertly experience his violent fantasies...it also allows him to frame his actions in a way that is justified, controlled and rationalized in his own mind.”
  (Dr. Engels, 34:06 – 35:03)

Important Segment Timestamps

• Introduction of Mark Twitchell & Setup – 00:01 – 03:15
• Analysis of Mark’s Childhood Fantasies – 04:15 – 08:52
• Online Deception & Early Marital Collapse – 11:12 – 12:26
• Star Wars Fan Film & Career Aspirations – 12:26 – 17:46
• Obsession with Dexter: Genesis of House of Cards – 17:46 – 25:35
• Psychological Escalation and Self-Identification – 25:35 – 29:13
• Setting Up Real-World Crime – 29:13 – 34:06
• First Attempted Murder (Gilles Tetreault) – 35:50 – 40:01
• Rapid Escalation, Selecting New Victim – 41:41 – 43:56

Tone and Host Dynamics

• Vanessa’s narrative is detailed and empathetic, anchoring events in emotional context and storytelling.
• Dr. Engels provides steady, clinical insight—consistently grounding the story in psychological theory and forensic patterns.
• The episode employs a careful balance of suspense, compassion for victims, and clinical detachment, all while directly engaging the true crime and psychology-savvy listener.

End of Part 1 Summary. Part 2 promises to uncover the horrifying outcome of Mark’s next steps, the fate of John Altinger, and the full psychological unraveling of “The Dexter Killer.”