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The late Heath Ledger was so obsessed with his "Dark Knight" character The Joker that his New York apartment was essentially a shrine to the super villain, according to a new report.

The New York Post said that when officials entered Heath's apartment in responding to his overdose in 2008, they "walked into a world filled with Batman comic books, literature on the Joker and clowns, small clown statues and recordings of Ledger practicing his oddly shifting Joker voice in high and low octaves."

A law enforcement official said Heath was "studying up on the origins of clowns and all of the previous Jokers like Jack Nicholson's character and Cesar Romero's, who was the first Joker on TV... He was trying to make his role different from the roles of the other actors. He was even studying how to make his voice different from theirs."

The iconic actor died in 2008 in his apartment at the age of 28. His body was discovered on his bed by a masseuse who had come for a scheduled appointment.

Heath's apartment was "immaculately clean," the source told the Page Six gossip section of the newspaper, adding that all the Joker research was neatly stacked.

"He was a perfectionist who clearly had a lot of respect for the character. All of that stuff was very tidy. He cared a lot about it," the source said.

Prior to his death and while filming "The Dark Knight," Heath kept a chilling journal that had "The Joker" emblazoned on the front. Inside, contents included ominous photos, comic strips and drawings of the movie villain, clowns and hyenas. On the back of one of the pages, he scrawled the words, "bye bye."

Before his passing, Heath spoke to Empire Magazine about how he formed his Joker character.

"I sat around in a hotel room in London for about a month, locked myself away, formed a little diary and experimented with voices — it was important to try to find a somewhat iconic voice and laugh," he said. "I ended up landing more in the realm of a psychopath — someone with very little to no conscience towards his acts. He's just an absolute sociopath, a cold-blooded, mass-murdering clown … Nothing intimidates him, and everything is a big joke."