true crime

She Thought She Found the Zodiac Killer. Then a True Crime Show Proved Her Wrong.

Susan Mustafa.
Susan Mustafa. Photo: Courtesy of FX

At the end of FX’s The Most Dangerous Animal of All, journalist Susan Mustafa says she’s planning to “get drunk as shit” and “burn the fuck out of that book.” The book, of course, is the 2014 best-selling memoir The Most Dangerous Animal of All: Searching for My Father and Finding the Zodiac Killer, which she co-wrote with Baton Rouge businessman Gary L. Stewart.

Mustafa and Stewart met in March 2012 through a mutual business contact, when Stewart was looking for a co-writer to help him with the story of his life. In the book, they follow Stewart’s search to find the biological father who abandoned him and whom Stewart became convinced was the Zodiac Killer, the unidentified serial murderer who terrorized Northern California in the late ’60s and ’70s. Through circumstantial evidence, including partial-fingerprint evidence, partial DNA, and handwriting analysis, the book concludes that Earl Van Best Jr., who had a sordid criminal history, was Stewart’s father and the elusive serial killer. Van Best Jr., Stewart also learned, had eloped with his 14-year-old mother, got her pregnant, and later abandoned him as a newborn.

In the four-part docuseries, streaming on FX on Hulu, executive producer Ross Dinerstein and director Kief Davidson conducted their own investigation of Stewart’s findings and debunked all of his theories. The producers didn’t share with Stewart or Mustafa what they uncovered until they conducted their last interviews with them near the end of production. When they confronted Mustafa with their evidence on camera, she was so upset she asked for a break. But in an interview with Vulture, Mustafa was forthcoming and apologetic as she spoke about where she feels she went wrong, her relationship with Stewart today, and how she feels about the documentary as a whole. “The lesson to be learned here, for me, is setting out to prove something as opposed to disproving something is a big mistake,” she says. “That’s a big mistake for a journalist to make. I have to own up to it. I have to take responsibility for it.”

How are you feeling now that you’ve had time to see the series?
It’s been a very rocky road for me. I’m a journalist and so truth is what I live and breathe. And the fact that there are discrepancies in the book has really been very difficult for me to deal with. I’m actually rather relieved now that the documentary is out there, because I spent months dreading what was gonna happen when it came out.

Let’s back up. The documentary covers some of this, but tell me how you met Gary and started working with him?
Gary was advertising in a magazine that I had previously worked for, and I was friends with the publisher. Gary happened to be in his office, telling him that he was looking for a writer for the story, and I happened to call at that exact moment. The publisher handed Gary the phone and said, “Man, have I got a writer for you.” Gary began to tell me a small portion of the story, and then he got his original manuscript to me through my publisher friend, and I read it that weekend.

That was his 500-page manuscript, right?
Yeah, it was very extensive.

From the series, it seems Gary was very meticulous and took extraordinary steps to find a lot of information. Was that your impression?
Yes, he did. As I read it, as it unfolded, there were some things in there that I was like, This doesn’t sound plausible. But as I saw the totality of his whole story, the “ice cream romance” between his mother and father, the abandonment of him in the town I live in, the reunion with his mother, and then his search for his father that led him to the Zodiac, it was an incredible story. I definitely wanted to investigate it further because it was so many stories intertwined into one.

What do you mean that some things seemed implausible?
Gary has a tendency toward grandiosity. It all seemed exaggerated in a way, but as I went through it and he started presenting his interactions with the San Francisco Police Department and his mother being married to [Detective] Rotea Gilford, it became fascinating to me. There were all these connections that I felt were worthy of an investigation.

When you started working together, did you investigate on your own, or did you base what you wrote on his findings?
Well, he had already done a lot of interviews. He had thoroughly researched the Zodiac Killer and presented me with documentation that bullet-pointed every connection that he had made to the Zodiac. There were some far-fetched things in there that I questioned him on, like Bobby Beausoleil of the Manson family playing in a band with his father in San Francisco during the Haight-Ashbury era. I was like, “Really, Gary? This sounds a little far-fetched.” And then he sends me an email from Bobby Beausoleil that says he was. Every time I questioned him on anything, he had the evidence to back it up for, either in emails or letters or police reports. So, at a point, I quit questioning him. That, to me, was the point that I lost my objectivity.

I should have questioned him on every detail. I should’ve gone behind him and interviewed everybody he interviewed. But the fact is he hired me to write this book based on his life story as part memoir and part true crime. So I didn’t question him. Normally, when I write a book, I do all of the research myself. But he did a large portion. The lesson to be learned here, for me, is setting out to prove something as opposed to disproving something is a big mistake. That’s a big mistake for a journalist to make. I have to own up to it. I have to take responsibility for it.

From talking to Kief and Ross and from what I saw on the show, I can see how, after spending some time with Gary, you let your guard down.
He spent two years working on this. He is a very likable person, but he’s also very filled with pain. And that pain draws you in. You feel that pain. And that’s why he is so convincing, because he absolutely believes everything.

Do you think Gary made a mistake, or was this deliberate?
I think he made a mistake. I don’t think Gary did any of this on purpose. I would like to be very clear about that. What I think now, honestly, is that he saw what he wanted to see and discarded the rest.

The series reveals that Gary doctored a police report, that he added information about his father being held at Atascadero when he wasn’t.
Well, here’s what happened there. In the original police report, the sentence for his father for fraud by wire was 90-day observation. Gary, in his original manuscript, had duplicated the police report, but he had taken out “90-day observation” and put in, “Atascadero, 90 days Atascadero State Hospital.” So, he didn’t alter the actual report. He changed it in his manuscript because he told me Lieutenant Hennessey had told him, “See Gary, you were right. Your father was in Atascadero.” So, I don’t think that was an attempt to deceive as much as what he believed at that time.

When they tell you on camera about all the discrepancies, you obviously got very upset. Can you tell me what that was like for you? Did you have any warning ahead of time?
No, I did not see it coming. Gary and I were told we were going to be doing our final interviews in Los Angeles, so we were excited. We believed all along that the documentary was following the book. We had no clue that it had veered off. Although, Kief was giving me hints like, “Susan, what would you do if you found out this wasn’t true?” But I had no clue that it wasn’t true. We were stunned.

They separated us that day and he did his interview first. I went for lunch with Rebecca Evans from Campfire [the production company behind the series], and she even asked me not to look at my phone because they were asking Gary the hard questions and they didn’t want him to give me a head’s up. They wanted my honest reaction. And so, they finished with Gary and they brought me in to the set. When I started realizing that things were going downhill, I just realized, Oh my gosh, they have found discrepancies in this book. I was devastated because my integrity means everything to my career and to me personally. And I realized my career was blowing up on me in front of the camera.

When I came back to Baton Rouge, I went into a really dark place. You believe you’re a good journalist, and then you find out you’ve made these incredible mistakes that are gonna be aired in a very public way. It’s a bad place to be. But I immediately pulled out the book and I marked up anything that could possibly be questionable, and I started investigating on my own. I went back and interviewed everybody who was still alive that I could find that had anything to do with Gary’s story. I went back through all of my research, every email. I wanted the truth. And so, when Campfire offered me the opportunity to interview [San Francisco homicide detective Gianrico Pierucci] on camera, I jumped on it. I knew that I was torpedoing my own career, but that’s how important finding the truth was to me. The truth was all that mattered.

Now that you’ve had some distance from it, do you feel your career was ruined, or was it just a bad bump on the road?
I hope that I will be able to recover. I’m a fighter. My integrity’s important to me, but I’m also going to take total responsibility for my role in it. I honestly no longer believe Earl Van Best Jr. is the Zodiac Killer. From everything Campfire uncovered and everything I uncovered on my own, I do not believe it anymore. What that’s going to do to my career, I still don’t know.

Do you have a relationship with Gary?
Yes, I do. When we were writing the book together, we were good friends. When the book came out, we went through a rocky phase, and then we were back to being harmonious again. And now we’re back in a rocky phase. He understands. I’ve made it clear that I will speak my truth and that I don’t believe his father is the Zodiac, but that I do care about him. He hasn’t tried to talk me out of speaking my truth.

The bottom line is Gary is a very complex person. I know that his obsession was what was portrayed in the documentary. He’s also a caring father, husband, a family man who honestly loves the people in his life very deeply. While we saw one side of him, there is a completely different side. And I care about him. And I feel bad for him. I’m sorry.

Do you think he still believes that the Zodiac Killer is his dad?
Yes, absolutely. Over the last 18 years, that has become intertwined into his identity. All he’s ever wanted to know was his identity, so it’s all a part of who he is. If that unravels, once again, he won’t know who he is. That’s a very hard thing for somebody who’s been traumatized to deal with.

One thing that stood out to me was, at the very end, we see him driving away with that “Van Best” vanity plate. What do you make of that?
I’ve wondered about that myself. I even asked him about it the first time I saw it. More than anything Zodiac–related, that’s part of his identity.

Did you burn the book?
[Laughs] Oh, gosh, if there were ever words you wish you could take back. I have not. Instead, I marked it up and went on a mission to find out what’s true, what’s not. People have suggested that I have a party and have a book burning, but I’m not going to do that.

Now that you’ve seen the series, do you feel it treated you fairly?
I think that Kief and Ross did an incredible job with it. They were very fair. Even though it’s not complimentary to me, they did their job much better than I did mine. And I’m very grateful to Ross and Kief for giving me the opportunity to redeem myself in the film.

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