Heath Ledger went crazy during Joker role?

He locked himself in his room for a month, getting used to the role, and getting into character. I think pretending and acting like the joker, made him believe he was, or could actually become the joker. Whenever I try and act like the joker, I think to myself "I can really picture myself doing this...it's fun" and I've always loved clowns and carnivals and all that amazing crap. But I'm also a huge freak, many mental characteristics...whatever...Anywhoooooo… think this role f*cked him up big time, and I can't choose if it's a great thing, or a bad thing, because it was the best joker and acting Ive seen. I couldn't even tell it was Heath, and didn't know until he fricken died! So, how do you think it went down..hm?...Do you think he went ka-rayyy-zehhh after trying so hard?