It wasn't hard drugs. It was sleeping pills. And you know WHY he was taking sleeping pills? Two words: THE JOKER. Ledger's commitment to the role led to him having sleep troubles. In November, The New York Times had an interview with him where he admitted that he was only getting 2 hours of sleep each night, that his mind was racing with ideas for the Joker character, and that he would take 2 Ambiens but STILL wake up just 1 hour later. His family also reported to the police that he had pneumonia at the time of his death, so sleeping pills + pneumonia looks to have been the biggest cause of his death. The police believe it's an accidental overdose and have said that NO HARD DRUGS were found in the apartment. Here's the interview I'm talking about:

http://www.nytimes.com/2007/11/04/movie … ref=slogin

He tends to do that. He is here in London filming the latest episode of the 'Batman' franchise, 'The Dark Knight.' (Mr. Bale, as it happens, plays Batman; Mr. Ledger plays the Joker.) It is a physically and mentally draining role '” his Joker is a 'psychopathic, mass-murdering, schizophrenic clown with zero empathy' he said cheerfully '” and, as often happens when he throws himself into a part, he is not sleeping much.

'Last week I probably slept an average of two hours a night,' he said. 'I couldn't stop thinking. My body was exhausted, and my mind was still going.' One night he took an Ambien, which failed to work. He took a second one and fell into a stupor, only to wake up an hour later, his mind still racing.