The relationship between he and his partner, the two seem so different.  Were the real people that different from one another?

Mark:  Totally different.  Dave Toschi was an anomaly. They were all dressed like G-Men.  They had their G-Men jackets and the ties and the G-Men glasses.  That was the prototype cop at the time.  Then you have this very flamboyant dude who wears bow ties and bright clothes and is very laizzes faire and so they had an interesting relationship.  It was contentious at times.

How close is the final film to the script that was originally presented to you?

Mark:  It was pretty close. I know there’s a couple of scenes cut out.  It was long.  It was longer than it is now so there was some stuff that was cut out that probably didn’t serve the movie totally but its pretty close.

What are you doing now?

Mark: I just wrapped a movie called Reservation Road that Terry George directed with Joaquin Phoenix and now I’m just hanging out with my kids.

Who do you play in that?

Mark:  It’s about a hit and run, two fathers.  I play a guy who hits his son and kills him and runs; a light, jaunty, romantic comedy [everybody laughs].

Is that an indie?

Mark:  Yeah, it’s Focus Films so it’s a mini-indie.

What’s it like going from a big picture like Zodiac to an indie? Is it totally the opposite?

Mark:  Totally, it’s fun.  I like that.  I get bored so I’ll say ‘let’s try this’.

Did you meet Robert Graysmith?

Mark: Yeah. I spent a lot of time with Robert.  Then, I met Narlow (Det. Ken Narlow). People were coming around as we were shooting; people who weren’t in the movie were coming around.  I met the guy who was stabbed at Lake Berryessa [Bryan Hartnell].  I met him and his kids.  There were a lot of people who were attached and part of this time.  Fincher and Brad Fischer were doing their best to get all of their stories and really make it an open place for them to come.

Has this experience whetted you appetite for contemporary murder mysteries?  Do you look at the paper and say ‘Wow, it happened again’? Do you get immersed in those cases?

Mark: No.  I’m too sensitive to it. It’s too scary to me.  The astronaut who went across the U.S. in a diaper, it’s hilarious.  It’s weird.

Anything about Fincher not in the press notes that you could tell us?

Mark:  I haven’t read the press notes but I was scared to work with Fincher kind of.  I had heard that he was an intense guy and sometimes, he yelled at people.  So, I didn’t know what to expect but I was really surprised by kind of how gentle and easy-going a guy he is.  Oddly enough, I was having a conversation with him and said something to me about having faith about where the world is going and everything.  It just struck me as odd from him in a weird way because he has such dark leanings.  But, he’s really an enormously optimistic and positive guy. He’s obsessive.  The film is kind of eating itself because he became obsessed with the case to down to when Arthur Leigh Allen died and they went to his house and gathered all the evidence, there was tape sitting in a cassette player and it was a tape of a child being spanked by Arthur Leigh Allen and it is the most gruesome and you want to kill the guy.  You do want to Dirty Harry his ass kind of.  But, Fincher was so obsessed that he knew about this tape, he heard it.  His obsession with the movie became the movie itself kind of.  He’s very, very meticulous.

Is that very far from other directors you’ve worked with?

Mark:  Michael Mann is a little bit the same way in a weird way.  He’s also a full frame director; likes to do lots of takes, very much immersed in the world that he’s creating, knows all the minute details, much more than any of the actors knows.  He knows more about your character than you do mostly.

Do you find that to be helpful?

Mark:  If they can convey it in a way that you can understand, it’s very helpful, yeah.  If it’s too much detail you just kind of shut down after a while. Do you know what Fincher’s idea of the perfect press junket is? ‘Everyone give us your questions.  Give us all your questions, give us a thousand questions.  Wherever they’re doubled, we’ll just ask them once, or tripled, we’ll just ask them once and we’ll sit down in front of a camera with mics and we’ll put together the entire thing and you guys don’t have to come here all day.  I think, ultimately, he really believes the proof is in the pudding and all the talking around it only clouds the issue.

Do you feel like that because you represent your movies very well?

Mark:  Well, I like to talk [everybody laughs]

Do you think is was Arthur Leigh Allen?

Mark:  I keep flopping back and forth.  I know they did this genetic test but we don’t know that it was his saliva on the back of the stamp.  I have seen this guy.  He was a bad, bad dude.  He was a sociopath.

He was guilty of something.

Mark: Yes. He also wanted people to believe that he was Zodiac.  Is it beyond a shadow of a doubt?  That’s where I’m stuck because there are those little things that don’t quite jibe.

But Dave Toschi thinks it’s him.

Mark:  Yeah and I want to believe it’s him too.  I really do want to think it was him.