Charlie Hunnam Lost 30 Pounds to Transform Into Ed Gein for ‘Monster’ (Exclusive)

It was no small feat for Charlie Hunnam to transform into a serial killer for the new season of Monster.

In the third iteration of the hit Netflix series, the actor, 45, plays infamous murderer Ed Gein — who went on a killing spree in the 1950s and robbed graves to use human remains to craft household items and clothing.

During a conversation with PEOPLE at the New York City premiere, Hunnam shares how he prepared for the intense role.

“I mean, finding the truth was the whole process,” he reveals. “We were much more interested in why Ed did what he did, rather than exploring what he did. Everybody sort of knows what he did, and it’s been chronicled in many films that he inspired and then direct adaptation to his life.”

He adds: “We, I think, felt confident that if we remain true to that, of just trying to find the truth in reflecting back this bizarre, tiny, dark corner of the human condition that he manifested, that we were staying true to the traditions of storytelling, which is to try to help us understand ourselves because we’re all so bizarre, even the most normal of us. But Ed was very bizarre.”

Along with tapping into a different mental state, Hunnam says he also made physical changes to more accurately embody Gein.

“He’d been abused, he was left in isolation, so he had no real social context to reflect back to him, normal behavior,” the Sons of Anarchy alum notes. “And he was a very skinny, malnourished type of guy. So I mean, first of all, basically the basic first step was losing 30 pounds so I could look like him.”

Something else that Hunnam dug deeper into was Gein’s relationship with his mother, who “told him every day of his life that she hated him because he wasn’t born the girl, the daughter that she always wanted.”

“Imagining what the consequence of that would be when she was the only person he had a relationship with,” Hunnam continues. “That really informed the voice work that we did and how he would interact with his mother and the world, which was really trying to really be the daughter that she wanted.”

Despite having to take on such a dark and traumatic role, Hunnam admits he never felt like it weighed on him outside of filming. In fact, he says the energy on set could not have been different from the story they were telling.

“There’s the subject matter and then there’s the actual process,” he explains. “We all felt really good about the work we were doing, and so actually in terms of the experience we had of trying to make this show every day, just the actual putting our craft into effect, it was actually really joyous and light. We were proud of ourselves and we were reaching for something.”

“And not every day, but more often than not, managing to grab a hold of it,” Hunnam shares. “So it was really actually, I don’t want to say a fun experience — that’s just going to be a terrible headline, that I think that this was fun, this impossibly bleak story — but it was a very satisfying and beautiful experience for me to get to work with [director] Max [Winkler], my dear friend.”

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Monster: The Ed Gein Story is available to stream on Netflix.