From an interview with Newsarama’s Daniel Robert Epstein:
"DRE: Have they given or asked you to read certain comics?
HL: The Killing Joke was the one that was handed to me. I think it’s going to be the beginning of The Joker. I guess that book explains a little bit of where he’s from but not too much. From what I’ve gathered, there isn’t a lot of information about The Joker and it’s left that way.
DRE: Is doing the role of The Joker scary after Jack Nicholson did it so well?
HL: I’m not going for the same thing he went for. That would be stupid. It is also two very different directors with different styles. Tim Burton did a more fantastical kind of thing and Chris Nolan is doing nitty gritty handheld realism. I love what [Jack] did and that is part of why I want to do that role. I remember seeing it and thinking how much fun it would be to put on that mask and attempt to do something along those lines. But it would obviously be murder if I tried to imitate what he did."
Click here for the full interview.