Cameron Britton. Photo: Ilya S. Savenok/Getty Images for Vulture Festival

Fans of the Netflix FBI drama Mindhunter will immediately recognize Cameron Britton as the terrifying serial killer Ed Kemper. Britton does such a hauntingly fantastic job portraying the killer’s mannerisms, it’s hard to imagine him doing anything else before playing a murderer. But he did! And, weirdly enough, one of his past jobs was as a preschool teacher.

During Sunday’s Mindhunter panel at Vulture Festival, moderator Abraham Riesman asked Britton about his career switch. Britton says he worked with 18-month-old to 3-year-old children with special needs for over eight years before he decided he should take his love of entertaining and expand it to a wider audience. Reflecting back, the actor realized that being in charge of small emotional children actually helped him immensely with portraying Kemper.

“[The children’s] impulses can get really intense and everyone is looking at you as the teacher and you can’t break, you know?” said Britton. “Or you lose, you lose the room. So I started slowly learning how to train myself to just cut all emotions out and just get rid of them entirely so I could be this serene presence … I’m not kidding, some days were pretty wild … after three hours of that class I would go into the bathroom and tears would well up [because] the emotions would just come back.” Said the actor, “That started becoming a mechanism, a physical thing to cut your emotions out. So when it came to playing Ed, it was actually really helpful.”

Now, some people even refer to Britton’s old preschool as the place where “Ed Kemper” used to teach. But just because Cameron Britton has a new terrifying gig doesn’t mean he plans to stop working with children. In fact, he was still babysitting while filming season one. Luckily, his clients were fine with his sinister day job. Said Britton, “Her mom was an industry type so she wasn’t creeped out or anything.” Many of the children Britton worked with are still too young to watch the show, but he realizes how strange it will be for them if they eventually tune in. Said the actor, “I do like to think that one day these kids will grow up and their parents will be like, ‘You see that guy? He was your babysitter.’”