you ask a guy about the dangers of obsession and his answer turns into yet another dissertation on his obsession, you know you’ve got the real deal. Robert Graysmith, the basis for Jake Gyllenhaal’s character in David Fincher’s Zodiac, is that real deal. I talked to Robert when the movie first came out, but I knew this guy had a lot more to say about the Zodiac case and the film version of it. I was right – this interview was short but could have gone on for hours.

Zodiac is now out on DVD, and you should check it out. It’s one of my favorite movies of the year, and if the box office receipts tell me anything, you probably haven’t seen it yet. It’s a crime that a movie as assured, wonderful and deep as Zodiac could be ignored by audiences, but hopefully the new DVD – and next year’s major director’s cut edition – will fix that.

Click here to order Zodiac from CHUD (you need to have the theatrical edition if you’re buying the director’s cut!).

My recorder wouldn’t start at first, so I have no idea what my initial question was for Graysmith. That said, I don’t think it matters – this guy just launches into topics at will, so let’s just jump in.

If you have an hour I’ll tell you what David Fincher did. First of all, one day you have to meet David Fincher – he’s the smartest guy I ever met. He’s ethical, he kept his word, but what’s amazing is that he became obsessed with the case like every single person who came into contact with it. Part of that, I think is because he grew up in [Marin County], and was one of those kids on a school bus that Zodiac threatened to attack. First of all, I gave him all my documents and set him up with as many people as I could. But on his own, he and his producer Brad Fischer and screenwriter Jamie Vanderbilt uncovered so many new clues I couldn’t believe it – new witnesses, a map of Lake Berryessa signed by the prime suspect, a parking ticket that places him in San Francisco on a day when one of the letters were mailed. I wrote a book about this, which I just finished the other day, called Shooting Zodiac, and it’s literally about three Hollywood detectives trying to greenlight their movie, and in some cases I think they actually outperformed the police.

I had spoken to you when the film was released, and you had mentioned Shooting Zodiac at that time. What’s the status of that? Is it being published soon?

I just love writing them. I go from one to the other. I haven’t offered it to a publisher, but I’ll probably go to Warner Books, which really just makes sense. You hear these stories about Hollywood, but I’m in a situation where I’ve done several of these, and in every case they absolutely kept their word, never disappointed me, and you could have done it on a handshake – that’s how honest these people were. Warner Bros in Shooting Zodiac come across as a hero. You hear a lot of bad things about them, but I think they would love to publish it because they actually saved the film. My book ends with the movie being greenlit, and never goes into the filming, but it’s an extraordinary thing to watch these guys write the script and get hooked on the case and find these clues.

I may have told you before, but I love the scene where I took David Fincher to Lake Berryessa. We had had some floods and stuff, and along with us was the original investigating officer on the stabbings at the lake. ‘This is where the stabbing took place,’ he tells us. Fincher looks puzzled, and he looks at how sound carries and the action of the waves and tests the ground and looks at the road that leads away from the murder site. Then he walks away and he’s like 50 yards away and does the same thing, testing the earth, checking out vantage points, calling out to see how far sound carries, then comes back and says, ‘No, the murder site is over there.’ The [police officer] said, ‘Oh my God, I took you to the wrong spot!’ That’s how good Fincher is, he’s like Sherlock Holmes. Just using how deep the footprints go into the sand and how the killer could have seen the picnic blanket from the road he worked out even with the contours of the lake changed from the rains and flooding the actual spot.

Where’s the point where being obsessed with something becomes destructive?

You don’t really know it. I realized I was obsessed when I saw Jake in the movie; you’re simply not aware of it. I was talking to David Fincher, when he was putting it all together, and he asked me what I would do in a day, and I said, ‘Well, I worked at the Chronicle and then, at about ten at night I’d go sit in front of the suspect’s house.’ As if everyone did that! That was my mindset; to me it was perfectly normal and very logical. I guess that’s why they call it obsession – when you’re in the grip of something like that you don’t realize it. Of course, I’m a very single minded person. Once I begin a project there’s nothing going to stop me. That’s why I’m sitting in room with 21 books I’ve completed. I love doing this so much I’m not even necessarily going to show them to anyone. They’re all illustrated and on everything from art history to… I just have the best time doing this stuff. And I get to talk to the most interesting people. I talked to this fellow who was a crime boss in Vallejo to whom Arthur Leigh Allen had admitted, ‘I am the Zodiac.’ I got him to tell this story three or four times. Apparently a number of years ago our leading suspect, who you see in the movie, didn’t just open the handle of a door to get at this guy, he split the door down the middle and came into the room with a hunting knife. That is one bad guy. Listening to this fellow, what’s interesting is that the story never varies.

A lot of pieces keeping coming together, in no small part thanks to David Fincher who uncovered 31,000 documents and interrogation tapes and witnesses who now identify the main suspect. Lots of great stuff. Brad Fischer, the producer, uncovered a map of Berryessa signed by the main suspect. They uncovered a parking ticket from San Francisco from the day one of the letters was mailed. My hat is off to them. I was lucky enough to follow them around and see their adventures and all their negotiations that went into getting a film greenlit.

You’ve had two good experiences with Hollywood now – have you considered going into screenwriting?

I’ve considered it. I could write a screenplay if it had no words; I’m basically visually. If it was a silent movie. After meeting Jamie and seeing how he works – he sold three screenplays while he was in college, to give you an idea how talented this guy is – but basically simplify, simplify, simplify [is his rule] so I’ve been trying to apply those techniques to my own work. I think it’s such a discipline and there are so many people involved in producing a movie, it would just… I’m a work alone kind of guy. I’m not sure I could handle a screenplay.

What are you working on next?

You’ve got to realize I get up in the morning and work through the day, so I’m way ahead. The next one is called The Laughing Gorilla, which is about police corruption in San Francisco during the Depression and an uncaught serial killer called the Gorilla Man. All true of course. We do corruption so well in this city – there was a beat cop with $800,000 in his checking account… in the Depression! First rate corruption. So I spent a few years on that. But I enjoy the process; I like to work from original documents, since I don’t trust second hand stuff. To see these people and then to find these little threads – the facts are there, but the facts suggest the story. When you see for instance that one of the detectives had been demoted by this corrupt chief and kept turning up at these Gorilla Man murders, what his motivations are, it all starts to make sense and is all thrilling.