Charlie Hunnam's prep for Monster: The Ed Gein Story led him to some "crazy s***," including somehow discovering a recording that Netflix's "best researchers couldn't get"

In order to get the voice of serial killer Ed Gein just right for the third season of Netflix's Monster, Charlie Hunnam went down a dark rabbit hole that led him to a rare recording that even Netflix couldn't find.

"Our best researchers couldn’t get it," director Max Winkler told Variety. "But Charlie got it, because he’s Charlie and he does crazy shit." It's important to known that Gein, like most famous serial killers, has a specfically unsettling voice, with Winkler putting it somewhere between Mark Rylance in the play Jerusalem and Michael Jackson. Because the murders, as well as Gein's subsequent arrest, took place between the 40s and 60s, there isn't much record of his voice – save for a few grainy recordings.

According to Hunnam, he reached out to Joshua Kunau, producer of the documentary "Psycho: The Lost Tapes of Ed Gein." Kunau handed over a 70-minute interview with Gein, conducted by police the night he was arrested.

"I started to see him through a series of affectations to please his mother," Hunnam said. "That’s where the voice came from."

If you aren't familiar, Gein is the farmer-turned-grave robber who murdered several women, in addition to digging up corpses from graveyards in order to make clothing and keepsakes from skin and other body parts. These horrifying acts would go on to inspire horror movie villains as Norman Bates from Alfred Hitchcock's Psycho (mainly due to Gein's extremely strange and toxic relationship with his mother), Buffalo Bill from The Silence of the Lambs, and Leatherface from The Texas Chainsaw Massacre.

Monster: The Ed Gein Story is the third season of Ryan Murphy's true crime Monster series, with the first two following Jeffrey Dahmer and the Menendez Brothers. Both seasons earned a combined total of 24 Emmy nominations (and from what I've seen so far, I think this season will follow suit).

Monster: The Ed Gein Story lands on Netflix on October 3. For more, check out our list of the best Netflix shows, or keep up to date with upcoming TV shows.