I still remember the moment I found out Heath Ledger was dead. I was driving up the 10 freeway in Los Angeles on the way home and a Variety colleague called. "Did you hear about Heath Ledger?" "No." I'm thinking maybe there's some awesome news about the then upcoming film "The Dark Knight." "Dude, he died."

Crushing. We were robbed of an incredible talent that day. But one of the other things we we robbed of was the chance to really dissect and investigate Ledger's choices for his soon-to-be Oscar-winning role as the Joker in "The Dark Knight," as well as the opportunity to always go back and reflect with the actor as he, and we, spun away from its epic impact over the years. The mystery left as a result is singular and fascinating, serving only to elevate the performance in some ways, but I always felt a pang of sadness that we could never dig into the work with the artist.

A couple of early interviews exist, one in particular at Empire, which give us a glimpse of what Ledger was thinking. His process involved locking himself away in a London hotel for a month and piecing together a diary, he said. But beyond what director Christopher Nolan has referenced then and since, that's really all we've had or will ever have.

At a Film Society of Lincoln Center event last year, Nolan spoke at length in an intimate conversation about his work on the "Dark Knight" trilogy, and particularly opened up about Ledger's process. "Like a lot of artists, he would sneak up on something," Nolan said at the time. "So you couldn't really sit and go, 'Okay, you're going to do the Joker. You're going to show me what it's going to be.' You had to sort of say, 'Let's read this scene. Don't act it, just read.' And he'd sit with Christian and there would be a line or two where his voice was a little different, throw in a little bit of a laugh.

"And then we would film hair and makeup tests and try different looks, and in that, he'd start to move, and we'd have these rubber knives and he'd choose what weapon and explore the movement of the character. We weren't recording sound, so he felt quite able to start talking and showing some of what he was going to do. And in that way he sort of sneaked up on the character."

These nuggets are, of course, fascinating. While "The Dark Knight" wasn't Ledger's final performance on screen (that would be his brief time in Terry Gilliam's "The Imaginarium of Doctor Parnassus"), it was certainly his last significant one. And it was one that saw his family and "Dark Knight" colleagues, from Nolan to co-star Gary Oldman, accepting awards on his behalf throughout the fall of 2008.

The German documentary show "Too Young to Die" has done a piece on Ledger featuring an interview with his father, Kim Ledger. In it, Ledger presents his son's Joker diary, featuring Batman comic panels, the actor's hospital monologue, clippings from Anthony Burgess's novel "A Clockwork Orange" (which Nolan had sent to Ledger in order to give an idea of the director's vision of the character). The words "BYE BYE" are scrawled across the final page, a chilling farewell indeed. "It was hard to see this," Kim Ledger says in the video.

Take a look at the clip below. Thanks to Reddit for digging it up (and The Film Stage for finding it there). A translation accompanies it. You'll briefly see Ledger's Oscar and the foam packaging that accompanies it via travel. Kim and the rest of the family accepted it on Ledger's behalf on February 22, 2009, exactly 13 months to the day after the actor died of an accidental overdose of prescription drugs at his SoHo apartment. I've included their acceptance speech below as well.

"This is the Joker’s diary. In order to inhabit his character, he locked himself up in a hotel room for weeks. He would do that. He liked to dive into his characters, but this time he really took it up a notch.

"The hospital scene is interesting because when he was a kid, his sister Kate liked to dress him up as a nurse. He was really funny like that. He also was in the movie. 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. It was hard to see this."

Heath Ledger's Joker Diary