A German documentary reveals the diary that the actor used to create the Oscar-winning character of The Joker in The Dark Knight .

A German documentary about Heath Ledger has revealed the diary that the actor used to help him as he prepared to play The Joker in The Dark Knight.

Reddit user u2aerofan discovered the video online and posted it to the Batman subreddit.

In a 2007 interview with Empire, Heath Ledger described how he prepared to play the iconic character and mentioned a diary that he used in the process:

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 a hotel room in London 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. I ended up landing more in the realm of a psychopath — someone with very little to no conscience towards his acts. He's just an absolute sociopath, a cold-blooded, mass-murdering clown.

Via: empireonline.com