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‘Mindhunter’: The Man Who Plays the BTK Killer Followed His Neighbors Home to Get Into Character

Sonny Valicenti spoke to IndieWire about his mysterious casting process, David Fincher's secretive set, and getting "eerie" around L.A. for the good of the role.

Mindhunter - Sonny Valicenti Ending ADT Serviceman



Sonny Valicenti is making the most of his newly famous, mustachioed face.

“I go to a coffee shop fairly regularly in my neighborhood. Someone [on Twitter] had said, ‘Oh, I just saw the ADT serviceman at the coffee shop. I really wanted to talk to him and ask him to kill me, but I got too scared,’ or something like that,” Valicenti said in an interview with IndieWire. “Then I saw that he tweeted at me, saying, ‘Hey, was that you at the coffee shop? I was really afraid to talk to you.’ [So] I hope to be an eerie presence in coffee shops all over Los Angeles for the next few months.”

Valicenti may or may not have the time to creep out Los Angelenos, though. After teasing his character in various episode openings throughout Season 1, many expect more of the knot-tying, sketch burning, gun-toting Kansas man, billed only as the “ADT Serviceman,” in Season 2. But Valicenti won’t confirm or deny the widely-held belief that he’s playing Dennis Rader, the BTK Killer who murdered 10 people between 1974 and 1991, or if his character will be a larger focus in future seasons.

And that’s because he doesn’t know.

“I’m just as curious as you are,” Valicenti said. “I think the only information I have is from whenever I Google ‘Mindhunter’ Season 2, and I see what articles are out there.”

Netflix has ordered a second season of David Fincher’s serial killer drama, but that’s as much as anyone is saying. Such secrecy over what’s next befits a casting and shooting process that was cloaked in mystery from the get-go. When Valicenti was asked to put himself on tape, he was told the pages he’d read weren’t for his part — a common practice in Hollywood for filmmakers worried about spoilers.

“The process was about three weeks,” Valicenti said. “I put myself on tape twice, and, because I knew it was a serial killer, it was about coming up with a way to let this type of behavior come through, either in voice or in physicality.”

Even once he got the role, no one told him exactly who he was playing.

“ADT Serviceman was the main [name used on set], and I think in that first scene, the gentleman does refer to me as ‘Dennis.’ That was as far as it went,” he said. “All of the direction that I would get on-set– Mr. Fincher would always say, ‘Don’t play a psycho killer. What I’m interested in is the behavior of a man, of a person going through their day.'”

That was enough for Valicenti to dig in and research an array of murderers, from Dennis Rader to Ed Kemper to Charles Manson. He watched YouTube videos of their interviews and read up on their histories.

“There’s plenty of research to do, but I feel like the focus was mainly on the [character’s] desire as opposed to a specific person. My character being referred to as the ADT serviceman is really a great metaphor for what the work was about: It was less about trying to make it be Dennis Rader, or whatever serial killer, and more about just being a human being.”

To get into the serial killer headspace, Valicenti even practiced stalking his neighbors.

“One thing I did, a couple of nights, was I would walk the residential streets in my neighborhood, and I would pick like a young couple to follow home,” he said. “The main goal was for them, of course, not to know that I was doing that, but it felt important to feel that experience; to have it be night, have this very strange secret that I’m following these people, and really start to feel my heart race, start to feel kind of utterly alone while also being 15 feet away from people I don’t know.”

“I could only really stand it for a minute or two,” he said. “But that was enough information for me to kind of take away from it, in the event that there was going to be a scene [where I was] waiting in someone’s house for them to come home. […] ‘What would it be like if I thought this, or if I had this desire?’ And, really, you can only stand those thoughts for a second. You take the information and run.”

David Fincher at Bafta's 'Life in Pictures' Series at Bafta PiccadillyDavid Fincher at Bafta - 19 Sep 2014

David Fincher


What he learned served him well once he got to set, but not in the way he expected. Though Valicenti said he knew of Fincher’s reputation for shooting dozens if not hundreds of takes, experiencing it was something else entirely.

“You really can’t prepare yourself for the emotional tailspins you go through on take 35 or take 45,” he said. “There were things that I had prepared, whether it be a specific way that I was going to move my body or a specific voice that I was going to use in take 10, but all of that was stripped away, which sort of left me very exposed. Then by take 35, I wasn’t quite sure what I was doing anymore, other than completely surrendering to his direction.”

And surrender he did. Because Valicenti didn’t have context for events outside the specific scene he was shooting, he learned to trust Fincher with every decision on set.

“Physically, emotionally, and mentally, everything was choreographed,” he said. “It was like a really great obstacle course for me to go through. […] There was always a part of the scene that I didn’t necessarily decide how I was going to do it because I knew that I was going to get very specific direction, sometimes down to the shape of my mouth on a very specific word, or, ‘Don’t blink until this line.'”

“I had watched an interview, I think it was Robin Wright, and she was talking about a piece of advice she got from David Fincher and, really, it was just behavior over time. As the shoot dates went on, I just started to see that when I’m focusing on the shape of my mouth on that one specific word, or when I blink, it’s all revealing something about the world of this character and, as days went on, my trust and sort of surrender to his process grew. I was very grateful for that, especially with the limited information I was given. I knew that when I got on set, I’d be totally taken care of.”

Throughout all of this, Valicenti didn’t know how his role would be utilized — in Season 1 or beyond.

“I didn’t know, and even when I got to set, there was mystery in the different departments,” he said. “I would sort of ask little questions, like, ‘Hey, do you know what this is about or how this fits into the story?’ They would just hand me a piece of paper that had a breakdown of all the scenes we were going to shoot and they’d say, ‘This is all we know. This is what we’re doing.’ That was interesting.”

Now, after watching Season 1, Valicenti appreciates how the ADT Serviceman is being handled.

“I think that the conversation of who this guy is — some people having a very, very sure sense of who he is and some people not knowing — I think sustaining, cultivating, and allowing for that mystery is definitely the goal of the show and the intention of Netflix. I think that’s part of the fun, and I’m proud to help sustain that mystery.”

“Mindhunter” Season 1 is streaming now on Netflix. 

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