Inside Heath Ledger's private diary: Batman star's heartbroken father shares personal notes from Joker journal

It was his greatest role that came at the greatest personal cost.
And now fans have been given insight into just how Heath Ledger became immersed into the dark world of the Joker.
While his official cause of death was an accidental overdose many have always believed the Australian actor struggled after he created his Batman villain.
For the first time Heath's father Kim has allowed the public to see just how dedicated his late son was to the Dark Knight character.
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Speaking out: As part of a German documentary called Too Young To Die, Kim Ledger revealed his son¿s preparation for the role that many believed contributed to his death in 2008

Going inside the role: The diary is a red and blue bound book filled with scribbled notes, drawings, photographs of clowns and bits of comic books

Last role: The actor in his final film part

On Thursday a short clip was released showing Heath's diary where he worked through traits and qualities he wanted the Joker to have.
Part of a German documentary called Too Young To Die, Kim reveals his son’s preparation for the role.
The clip starts with the older Australian man opening the red and blue bound book and showing the scribbled notes, drawings, photographs of clowns and bits of comic books.
'This is the diary,' Kim says in the clip posted to Reddit Thursday evening.
Sitting next too the star's Best Supporting Actor Oscar - which he won posthumously for the role - the diary shows that Heath took a lot of inspiration from Malcolm McDowell's character in a Clockwork Orange and even from hyenas.
'He pretty well locked himself up in a hotel room for weeks.
'He galvanized the upcoming character. That was typical of Heath.

Different inspiration: The diary shows that Heath took a lot of inspiration from Malcolm McDowell's character in a Clockwork Orange

Brilliance recognised: In the clip Heath's Best Supporting Actor Oscar - which he won posthumously for the role - can be seen

'He would do that. He liked to dive into his characters, but this time he really took it up a notch.
'He immersed himself in the upcoming character on every level level.'
A reminder of his son's early demise - Heath was just 28 when he was found unresponsive in His new York home in January 2008 - Kim did manage to find some of the diary amusing.
In one part Heath had focused on a scene in the hospital which reminded his father of when the actor was young.

Better memories: While the diary is reminder of his son's early demise - Heath was just 28 when he was found unresponsive in His new York home in January 2008 - Kim did manage to find some of the diary amusing

Dress ups: Kim liked a section where his son explored a hospital scene as when Heath was a child his sister would dress him up as a nurse

'The hospital scene is interesting because when he was a kid, his sister Kate liked to dress him up as a nurse,' Kim said.
'He was really funny like that. He also was in the movie.'
While Heath's death was ruled accidental the diary does reveal he was struggling with the deeply twisted role and his own emotions.

Telling: Heath had gone back and written over an image of a make-up test

As Kim nears the end of the book there is a picture of his son in the Joker costume for the first time and there is writing scrawled over it in big silver marker.
'This is a make-up test which was done eight months before. Before the end of the shooting he wrote ''bye bye'' on the back of the page,' his father said.
'It was hard to see this.'
The Australian actor left behind his daughter Matilda, whom he had with actress Michelle Williams. The pair were not together at the time of his death.

Final goodbye: Heath wrote on the diary's last page 'bye bye' something his father said 'was hard to see'

The Dark Knight was released nearly six months after his death.
Prior to his death he spoke to Empire Magazine saying he 'feared' the role but wanted to make it different.
'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.
'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, and Chris has given me free rein. Which is fun, because there are no real boundaries to what The Joker would say or do. Nothing intimidates him, and everything is a big joke.'

Tragic: The Australian actor left behind his daughter Matilda, whom he had with actress Michelle Williams, seen here in 2006