The "Brokeback Mountain" star plays the Caped Crusader's nemesis in "The Dark Knight" and claims he locked himself away to help get into character.(Heath Andrew Ledger [12/03/2007])
Heath told Empire magazine: "It's a combination of reading all the comic books I could that were relevant to the script and then just closing my eyes and meditating on it."
"I sat around in my London hotel room for about a month, locked myself away, formed a little diary and experimented with voices - it was important to try to find a somewhat iconic voice and laugh."
Heath was given permission by director Chris Nolan to portray The Joker - the part made famous by Jack Nicholson in the original 80s "Batman" movie, directed by Tim Burton - in any way he wanted, which resulted in the villain becoming a "psychopath."
Heath, 28, revealed: "I ended up landing more in the realm of a psychopath - someone with almost no conscience towards his acts."
"He's just an absolute sociopath, a cold-blooded, mass-murdering clown, and Chris has given me free rein."
"Which is fun, because there are no real boundaries to what The Joker would say or do. Nothing intimidates him, and everything is a big joke."