This Terrifying Serial Killer Could Make 'Mindhunter' Season 2 Even Creepier

An ADT Serviceman insists that someone bring him an empty roll of electrical tape before being given a new one. One episode later, the same employee stares at a house, then walks across the street into their van. The next episode, the man drops a letter into a mailbox. Who is this mysterious Kansas ADT employee in the Mindhunter opening credits, and why does each episode open with a short vignette following this seemingly mild-mannered stranger? This mysterious character isn't even given a name, referred to in the credits only as "ADT Serviceman," but he could be setting up the plot of Mindhunter Season 2.

Mindhunter Season 1 follows Holden Ford, played by Jonathan Groff, as he attempts to get inside the minds of various serial killers and understand their motives. Ford seeks to apply logic and reasoning to seemingly irrational actions. So what does all this have to do with a nameless ADT employee? Well, though Mindhunter doesn't name this serviceman throughout Season 1, this character isn't tough to figure out. This ADT Serviceman is named Dennis Rader and he was a real man who lived in Kansas in the 1970s. While he doesn't play a central role in Mindhunter yet, it is likely that he eventually will. After all, Dennis Rader went on to be known as the BTK Killer.

The BTK Killer was active between 1974 and 1991, killing a total of 10 people in the Wichita, Kansas area. As The Wichita Eagle reports, Dennis Rader began working as an employee of ADT Security Services in 1974, the same year he started killing. Per Fox News, the name BTK Killer is a self-given one, derived from a letter that Rader sent to police in which he admitted to murdering an entire family and stated that "The code words for me will be ... bind them torture them, kill them, B.T.K."

Mindhunter takes place in 1979, and the show's opening vignettes follow a series of events leading up to an attempted murder by the BTK Killer. As the Washington Post reported, "On April 28, 1979, the [BTK] killer waited for Anna Williams, 63, but she was at a square dance and stopped to visit her daughter, not returning home at her usual time." The vignettes follow a few days in the life of the BTK Killer leading up to this attempted murder, which included sending letters, observing houses, practicing knots, collecting tools for his murder, and eventually staking out a house waiting for someone to come home.

But on the show, as in real life, Anna Williams didn't come home as expected, since she went to see her daughter. One of the final BTK Killer vignettes of Season 1 show him pacing around a house that is not his own, wearing a heavy jacket lined with duct tape, ropes, and a gun, growing increasingly frustrated. Eventually he decides to give up and leave — just as he did in real life. According to The Washington Post, he later wrote a poem entitled "Oh Anna, Why Didn't You Appear?" lamenting the fact that he did not get to follow through with his plans. In the final scene of Season 1, he's seen burning crude drawings of bound women in a backyard — based on actual drawings attributed to the real BTK Killer.

While the BTK Killer doesn't play a large role in the plot of Season 1, chances are he'll return for Season 2 of Mindhunter. John E. Douglas, the man that served as the inspiration for Holden Ford, literally wrote the book on what it was like tracking the BTK Killer. The book Inside the Mind of BTK: The True Story Behind the Thirty-Year Hunt for the Notorious Wichita Serial Killer, written by Douglas, could serve as an inspiration for a future Mindhunter plot. If he is, then expect the hunt to take a long time — The BTK Killer wasn't caught until 2005 according to The Atlantic, over a decade after his final killing. The Wichita Eagle reported that Rader is "now serving 10 consecutive life sentences in El Dorado Correctional Facility." The BTK Killer may be looming in the background of Season 1, but expect him to play a much larger role as the series goes on.