Peters spent four months preparing for the role, taking into account every single detail of Dahmer’s physicality to ensure that his portrayal was as accurate as possible. “He has a very straight back. He doesn’t move his arms when he walks, so I put weights on my arms to see what that felt like,” he explained, per Variety. “I wore the character shoes with lifts in them, his jeans, his glasses, I had a cigarette in my hand at all times.”
Peters admitted he initially wasn’t sure about accepting the role of what he considered to be an “incredibly dark” character. “I really went back and forth on whether I should do it or not,” he said. “I knew it was going to be incredibly dark and an incredible challenge.” However, once he took on the role, Peters went deep, and according to series co-creator Ryan Murphy, “basically stayed in this character, as difficult as it was, for months.”
Peters’ co-star, Niecy Nash, said she tried to approach Peters when filming started, but noticed he was already “in his process.” While she wanted to respect his approach, Nash admitted she also kept him in her prayers because she understood the emotional weight that comes with playing such a challenging character.
“I wanted to respect that and I wanted to keep him there,” Nash explained. “I prayed for you a lot, for real, because this is weighty. And when you stay in it, and you’re tethered to the material, like bone to marrow, your soul is troubled at some point. And I could see him getting tired. I just said, ‘Well, I’m just gonna make sure I keep him in my prayers, because this is a lot and he wants to do it justice.’”
“I wanted all this stuff, these external things, to be second nature when we were shooting, so I watched a lot of footage and I also worked with a dialect coach to get down his voice,” Peters said. “The way that he spoke, it was very distinct and he had a dialect. So I also went off and created this 45-minute audio composite, which was very helpful. I listened to that every day, in hopes of learning his speech patterns, but really, in an attempt to try to get into his mindset and understand that each day that we were shooting.”
Peters called it an “exhaustive search,” while he was trying to find Dahmer’s “private moments,” the times where he “didn’t seem self conscious, so you could get a glimpse into how he behaved prior to these interviews and being in prison.”