Heath Ledger was not a happy man during the last months of his life.
"[Heath] had a stint in rehab late last year when he was treated for heroin," a source told the Daily Mail.
"Heath was shattered by his split from [wife] Michelle [Williams]. He became a recluse. He barely slept he was dealing with terrible mood swings."
"Heath totally wanted to be on his own these past few months since he and Michelle split in September," said another source. "She was very much in love with him, but the fact he continued to dabble in drugs kept their relationship from being one she could rely on.
"He adored his daughter Matilda, and when Michelle called it quits, he missed Matilda so much that he was thrown into a deep dark depression.
"Heath was living in New York to be close to his daughter. But he hardly ever ventured out anymore.
"His close friend and Brokeback Mountain co-star, Jake Gyllenhaal has been worried about him for months. And he knew Heath was sinking further into a depression. Jake is Matilda's godfather, and he and Heath had become really close since they did the film Brokeback together.
"Jake wanted Heath to get help, but he refused, and now it looks as though he may have died of a drug overdose.
"Michelle will be devastated by the news, because she always hoped he would get help and they could manage to work out their relationship for the sake of their daughter."
A source describes Ledger's disheveled appearance at a party last September:"It looked as if he was if he was trying to make some kind of point. He drifted around the party not talking to anyone for half an hour and then just walked off into the night like a lost soul. It was most odd.
"He and Richard Gere were both special guests at the party. But Heath was just like a ghost. It was obvious something awful had happened to him."
(source)