The garage was supposed to be empty. That’s what Giles Tetreault thought when he pulled up, expecting to meet a young woman named Sheena he’d been chatting with online. Instead, a man in a black hockey mask with gold stripes lunged at him with a stun baton. Tetreault fought back.
Hard. He broke free, stumbled to his car, and drove away, his heart hammering. He didn’t call the police. He was married, and he was ashamed.
He told himself it was some sick prank and tried to bury the memory. A week later, a man named Johnny Altinger told his friends he was going on a date with a woman he’d met on a dating website. He never came back. At first, his friends weren’t overly worried.
Then they started getting emails from Johnny claiming his date had swept him off to Costa Rica for an extended vacation. That was the first red flag. Johnny hated hot weather. The emails didn’t sound like him at all.
When his employer received a cryptic resignation letter, his friends broke into his condo. They found his passport on the table, dirty dishes in the sink, and no sign of a packed bag. They called the Edmonton Police Service. A homicide investigation was launched.
Mark Twitchell was a struggling Canadian filmmaker with a deep obsession with the show Dexter. He had adopted the persona of the show’s fictional serial killer on Facebook and had written a screenplay for a Dexter fan film. He’d even built a makeshift version of Dexter’s infamous “kill room” in a rented garage, complete with a metal table and plastic wrap. When police first spoke to Twitchell, he offered a strange story.
He claimed Johnny Altinger had sold him his car for just $40 before leaving for Costa Rica, saying he wouldn’t need it on holiday. It didn’t add up. Officers searched Twitchell’s home and garage. They found forensic science books, guides to Costa Rica, a pile of blank postcards, and a black hockey mask with gold stripes that looked stained with blood.
When they impounded his car and laptop, they found a military knife stained with Johnny’s blood and a blood-soaked carpet in the trunk. Dozens of sticky notes were scattered around, bearing cryptic phrases like “kill room” and “clean sweep. ”
Twitchell was arrested on Halloween, 2008, and charged with first-degree murder. At trial, the crown presented the key piece of evidence: a deleted document recovered from Twitchell’s laptop titled “SK Confessions.
” It opened with the chilling line: “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. ”
The document described how the narrator lured men using fake online dating profiles targeting middle-aged single men.
It detailed his planned outfit—a black hooded jumper and a black hockey mask with gold stripes—and described the “kill room” with its metal table, just like Dexter. It also described a failed first attack, a man who survived a stun gun attack and escaped. Police knew Johnny wasn’t the first. They held a press conference, displayed the mask, and urged other victims to come forward.
Two days later, Giles Tetreault called. He was the man who got away. On the stand, Twitchell admitted to killing Johnny and writing the document, but claimed it was self-defense. He said the whole thing was a PR stunt for his movie, a way to create buzz.
The attacks were supposed to be elaborate fake-outs; all the victims were meant to escape. But Johnny fought back too hard, and the stun gun wasn’t enough. The killing was an accident, he said. The document was fiction “based on fact.
”
The jury didn’t believe him. After just five hours of deliberation, Mark Twitchell was found guilty of first-degree murder and sentenced to life in prison without parole for 25 years. But Twitchell wasn’t the only fan who took Dexter too far. In 2009, a 17-year-old named Andrew Conley strangled his 10-year-old brother to death.
He told police he watched a show about a serial killer, “and I feel just like him. ” After the murder, he put a plastic bag over his brother’s head, mimicking the show’s disposal ritual. He pleaded guilty and is serving life without parole. Copycat killings have existed for over a century, inspired by everything from Jack the Ripper to films like Natural Born Killers.
But the tragedy behind the fiction of Dexter proved that sometimes, the line between entertainment and reality can be terrifyingly thin. In the end, the show’s star, Michael C. Hall, said he was horrified that his role could have inspired such violence. But for Johnny Altinger, the metal table was real, and the mask was real.
The fiction had become fatal.
