Credit: Sarah Rhodes/Newspix/Getty Images

A German documentary about the life of Heath Ledger is giving a glimpse into how he created his chilling Joker for The Dark Knight.

A scene from the doc shows Ledger’s father, Kim Ledger, leafing through a diary his son kept while preparing for the role.

“He pretty well locked himself up in a hotel, in his apartment, for a month or so, to sort of galvanize the upcoming character in his own mind,” Kim Ledger said. “That was typical of Heath on any movie. He would certainly immerse himself in the upcoming character. I think this was just a whole new level.”

The diary is filled with images of playing cards, scenes from Batman comics, photos of hyenas, and stills of Alex DeLearge from A Clockwork Orange. The word “Chaos” can also be seen, written in caps and highlighted in green.

Ledger died in January 2008 at the age of 28. The following year, he was awarded a posthumous Oscar for his role as the Joker, and that statuette can be seen in the clip below as his father looks through the diary.

The Dark Knight
  • Movie
  • 152 minutes