The author talks about why he went after a serial killer and what it's like to work with David Fincher

When Robert Graysmith begin trying to figure out the clues that the Zodiac Killer was sending into the San Francisco Chronicle, he had no idea that his work would lead him to basically go after the killer himself and write two novels about it, Zodiac and Zodiac Unmasked: The Identity of America's Most Elusive Serial Killer Revealed. In David Fincher's interpretation of Graysmith's book in the film Zodiac, we see Graysmith's character (played in the film by Jake Gyllenhaal) begin a labyrinthine quest (along with others) to try and find one of the most notorious killers ever to stalk the Western hemisphere.

We recently caught up with Graysmith to discuss the movie and his contribution to this fascinating case.

What was it for you about the Zodiac case that made you go after the killer the way that you did?

Robert Graysmith: Well, first of all, I am the luckiest guy in the world because I've had such a wonderful movie experience. I love movies. This is my second film and as far as what made me go after Zodiac, once again that's why I brought up luck. I was just at the right place at the right time. I was in my early 20s. A young cartoonist from a very small paper, and I'd go into this great boardroom where the governor of the state had just been sitting, Dianne Feinstein comes in all the time, all these heavyweights and here come these letters. The next thing I know, I'm back at my desk drawing a cartoon and there's Paul Avery (Robert Downer Jr.) and news cameras.

To see it build right in front of me, to see those letters... because they came to "Letters from the Editor." Carol Fisher (Candy Clark) would open them as you saw in the film. Gradually, to watch inspector Toschi (Mark Ruffalo), there was a point where they were not getting it done. I realized I had the chance because as a political cartoonist you work with symbols, you use the exact same material that Zodiac is using to instill fear, I could use those same symbols in a book by putting together drawings and maps; everything I could find out about this guy, and effect change, just by what a political cartoon does, and catch him. Just put the information out there and let the American people get him.

So, that was my plan and I just didn't realize it was going to take me until 1986 to do that.

This movie feels very structured, very by the book, it shows us two versions of the Zodiac killer being hunted down. What is your opinion of the movie seeing as how it's based on the material you've written?

Robert Graysmith: Well, of course it's the finest film ever made! (Laughs) Once again, David Fincher, as we all know does not to be photographed, doesn't like to be interviewed so naturally, for three years, while they were writing the script and finding new facts and clues and you name it... taping and photographing endlessly. To see the amount of care that goes into a film, now I know Fincher does 70 takes before breakfast... I know he's a perfectionist but I had no idea, in this hotel room in San Francisco, I'm watching them work on this script. He gets Brad Fischer, who's the producer on the film... and he's sitting in this chair pretending to the cab driver and David Fincher is trying to rip off a piece of his shirt, trying to extract his wallet and just constantly reworking the position. "Why was he here?" "Why was the clue there?" That was 3 hours.

So you flash ahead months and months and months he's still asking, "Why was that door left often?" "Did somebody touch it when the police came?" He's calling in these people, he's walking in the scenes... things that don't even show in the film. There's just a quality to this guy. Frankly, I think he's in the wrong business. I think David Fincher should probably be an 18th Century Landscape painter because he has this temperament. There is that temperament where you're focused on what you're doing and you know what you're doing and you're going to get it done.

I love the scene at Berryessa in Zodiac where I've taken Brad and all the original investigators, Dave Fincher and James Vanderbilt and the guy who had originally discovered the stabbed victims at the lake. He takes us to the spot and he says, very firmly, "This is the spot, this is where it happened." David Fincher looks a little quizzical at him and he studies the road that looks down on the site about 520 yards away, he makes a yell and listens to how the sound carries, and he feels the ground to see how rough it is and how spongy it is. Without a word, he walks away. We see him on another inlet. Here he's a tiny figure and he's doing the same thing. He comes back and he says, "No, you're wrong. The murder site is over there." The guy who had originally discovered the scene says, "My god you're right, I took you to the wrong spot!" I was literally blown away. I was converted at that moment.

What for you was the toughest part of going after Zodiac?

Robert Graysmith: I'm not a very logical personal. You've got to realize you couldn't Star 69. There was a phone number in Darlene Ferrin's purse written on an old photo pack, where you get the photos back in those days. I didn't want to dial the number because I thought it was an important number. She'd written the word "hat," "testify" and some other things that sort of led me to believe this was an important number. So I literally took the the phone book and went through, number by number, until I matched it visually. We had 2500 suspects and because I worked for a newspaper we had a requester code that allowed me to tap into the state... I could find out weight and height and if they'd had an accident... so pretty good stuff so that we could whittle these people away.

We knew that he had been supposedly at Riverside, at the college there, so I was going through the signatures, the forms that were filled out looking for handwriting matches. That's very time consuming, very low tech and of course things like the postmark, we didn't know those. Literally, they would not allow you to write a lot of this stuff down, if you could come close to guessing some of it they might tell you something. Just getting stuff, nowadays, freedom of information act, I imagine you could get it immediately. Just every fact was extraordinarily difficult to withdraw, that was very daunting and probably why it took me 10 years to finish the book.

What was the scariest moment that you experienced going after the Zodiac? Was it that scene under the stairs?

Robert Graysmith: You nailed it. That was really foolish, to go there at midnight. There definitely was someone up there. Of course we had a second suspect who, some of the policemen, think is a pretty good suspect. Obviously he's up there, he knows that's why I've come and you could hear that heavy tread. That was totally true and it was extraordinarily foolish on my part. The only difference from that than real life is that the guy had a train set and I think he had two silent movie posters on the wall. They just recreated it exactly. I wanted to see it with Dave Toschi so I went to see it at the premiere in San Francisco... our lips just moved along with the dialogue. They recreated his house and my old apartment.

What are you working on now?

Robert Graysmith: Thank you for asking. I'm looking at my computer... I've got on my screen right now Shooting Zodiac which is those three years I followed David Fincher around taking his picture and all that. It's an odd choice for a book. Usually, they do something as they're filming. Well, my book actually ends before they film anything. It's just simply them writing the script and all their adventures and becoming obsessed with the case. Also, trying to convince the studio to make this film. It simply ends with, "We've been greenlit, we're making the film." I love that. It's simply three Hollywood detectives. I think it really gets down to that.

I've finished something called The Laughing Gorilla which, nobody does corruption better than San Francisco. It's 1935 and it's the police force and this is the depression. One cop has $856,000 in his checking account, a lot of them have $200,000 so it's marvelously corrupt. The city's Public Defender has murdered a woman. They're on the lookout for a guy called The Gorilla Man who actually scared me. It's a fascinating story because they don't understand what's going on. We would understand what's going on but in those days the police would have no frame of reference for something like The Gorilla Man.

Zodiac comes to DVD July 24 from Paramount Home Entertainment.

Dont't forget to also check out: Zodiac