To go "method" some actors lose weight or work part-time at the jobs held by their characters. For Jamie Dornan, he took it a step further – following a woman on the subway as background research for his role as psychotic serial killer Paul Spector on Netflix crime thriller "The Fall."

Much like his trip to a sex dungeon to prepare for his role in "Fifty Shades of Grey," the Irish actor went to even crazier extremes to get into the mindset of a sadistic murderer.

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Speaking with the Los Angeles Times on Monday, the 36-year-old Dornan hesitantly opened up about his method of getting into the headspace of a serial killer.

"The first series, I did do a couple of things to try to get inside [his mind]. On the tube, which is our underground system-" Dornan said before stopping himself, fearful that he might face legal repercussions for his intense preparation. "Can we get arrested for this? Hold on ... this is a really bad reveal: I, like, followed a woman off the train one day to see what it felt like to pursue someone like that."

Dornan detailed his experiment, explaining that he kept his distance from the woman until she reached her exit, and then followed her clandestinely for a few blocks in order to feel just a bit of what his character feels when stalking a victim.

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"It felt kind of exciting, in a really sort of dirty way," Dornan revealed. "I'm sort of not proud of myself. But I do honestly think I learned something from it, because I've obviously never done any of that. It was intriguing and interesting to enter that process of 'what are you following her for?' and 'what are you trying to find out?'"

In "The Fall," Dornan's Spector is a father, a husband, and a lunatic who revels in tying up women before murdering them. The series follows Spector's life of crime and the investigation conducted by Detective Superintendent Stella Gibson (Gillian Anderson) who is trying to catch him.