Josh Hartnett shares what he learned about himself after studying serial killers for Trap role

Josh Hartnett studied serial killers for his latest movie role.

The 46-year-old actor made his name in the late 1990s on the drama series 'Cracker ' and then starred in a string of comedies like '40 Days and 40 Nights' but revealed that he delved into the world of murder to play a serial killer in his new film 'Trap'.

He told Britain's HELLO magazine: "Yeah, my character is basically a serial killer. He's no hero - although he is to his daughter and to those around him. He's a sociopath with a very, very dark secret. It's a secret that is suddenly at risk of being exposed when he takes his daughter to a concert which, you discover, is a trap to capture him. At this point he'll do just about anything to maintain his cover, to not get caught and to not be exposed as the serial killer everyone has been hunting for.

"I have always been a huge fan of [director] M. Night Shyamalan's work. Secondly, reading the script and understanding this is a story that actually happened - in Washington DC in the 1980s. They set up a bunch of felons with Super Bowl tickets and the cops were waiting, disguised as cheerleaders and mascots."

"I studied serial killers and one of the things I learned is that even serial killers can be loving fathers. I read a great book called 'The Psychopathy Test' which outlined how something like ten per cent of us have sociopathic tendencies."

The Hollywood star - who has four children with his wife Tamsin Egerton - was pleased to discover that he did not have any sociopathic traits himself and admitted that the only thing he has in common with his character is the fact that they are both dads.

He said: "Other than being a father, thankfully not. I would say this character is just about as far removed from me as could be. Pretty much all of it was far outside of anything I have ever experienced before, but that's the fun part of being an actor. You learn, you adapt and you try to do something different to play a character as different from yourself as you possibly can. That's the challenge."