Former Los Angeles deputy district attorney Marcia Clark, who was the lead prosecutor in the O.J. Simpson murder case, and reporter Sebastian Rotella, a former Mexico border correspondent and bureau chief in Paris and Buenos Aires for the Los Angeles Times, both took the “write what you know” adage to heart when they sat down to write their first novels. Clark’s novel, Guilt By Association, out in April, concerns Los Angeles D.A. Rachel Knight, who takes on the case of a young woman who was assaulted from a prominent family. Rotella’s novel, Triple Crossing, an August publication, is a thriller about the criminal underworld at work along both sides of the U.S.-Mexico border, and a young cop who goes undercover to bring it down. Here, the two writers talk about how their day jobs have influenced their writing, in both obvious and subtle ways.

Marcia, in a note to readers, you say that when you started writing your novel, you sent chapters to an agent but “she hated them.... I decided I was nuts to think I could write and went back to my caseload.....” Did being a prosecutor give you a tough skin?

Marcia Clark: It was awful! As a prosecutor, I’m never fighting for myself; I’m fighting for someone else. There’s a sense of championing another person’s cause. That does not prepare you for championing your own cause or for the rejection when you fail. It knocked me pretty flat. I literally hunched over my keyboard and thought, “Why did I do this?” [But after some guidance], that kind of propped me back up and I said, “Maybe I can do this.”

Sebastian, how did your journalism career prepare you for writing a novel, emotionally?

Sebastian Rotella: As a journalist you deal with rejection and reader response at all kinds of levels. And when you’re trying to get people to talk to you, situations can be uncomfortable or harrowing. That gives you a tougher skin, without a doubt.

How was the day-to-day of writing a novel different from your “normal” life?

SR: It was great. This novel examines some of the places and themes that I covered in journalism that were the most dramatic and intense for me, the underworlds of the borders of South America and Mexico. When you’re writing newspaper stories, you can convey some of the intensity of the experiences, but ultimately there’s a limit to what you can describe. Being able to explore that world much more profoundly gave me a whole different sort of parallel life. I wasn’t necessarily covering things that I was writing about in the novel during the day, but you’re always learning on the job, and it all helped inform what I was doing as a novelist.

MC: When I was writing the novel, I was handling a full caseload, which is an 80-hour-a-week job by itself. There is something really cool about going from one world to another. You have the ability to expand in a book in a way you don’t have anywhere else. You can enliven all sides of the characters. It was a beautiful experience as well as a totally exhausting one.

How about being edited? Was that like anything you’d encountered in your career in courtrooms, Marcia?

MC: Being edited was completely new. As a prosecutor, ultimately you deal with the rulings of the judge. You are not “the director of your movie,” as someone once said to me. That’s the biggest bullshit I ever heard. The judge can completely slash your plan with a bad ruling. And those rulings happen constantly, every time the judge says “overruled” or “sustained.”…. That’s a completely different thing from writing a book, where someone says, “Fix this,” and “Change that,” and you have the time to think about it, then either agree or disagree with it. I’ve heard the editing process can be a tough experience, but I was incredibly lucky. For me it was a wonderful experience because I had an agent and an editor who gave great notes. Every single one made the book better. I have to say, I loved every second of it.

You say you really struggled to find your “real voice.” How did you know when you’d found it?

MC: It just felt right. I had been trying to make [the lead character] too nice and a friend of mine read an early iteration and said, “Who is this? This is not you!” I looked at it and I said, “She’s right. What am I doing? I can’t pretend she’s someone else. I can’t write that person. I think the false note of that will come through, especially since this is intended to be a series.” If you want to have a lead character, that character has to have a real voice and one that I can relate to. I finally thought, “Let it all hang out.” I had to really get into her skin. Once I did, I could feel that it was easier. I wasn’t forcing, I wasn’t trying. I wasn’t overthinking. I was just writing how [the character] feels, how she speaks. It flowed better because there were no forced moments anymore.

SR: That was part of the liberating experience of writing a novel, for me. The constraints of writing journalism, sourcing, what you can and can’t say... it was liberating to get over the boilerplate prose of journalism and be able to do much more with points of view, language, and vocabulary. It took some time to make that transition as a writer. In Triple Crossing, there are two main characters: one is American and one is Mexican, and they both have very different and very specific ways of seeing the world and ways of speaking. Thatpart, creating those characters, was a lot of fun. But it was a challenge to construct a pretty intricate plot where there’s a lot going on, that is also artful and contains suspense.

What about plotting for you, Marcia?

MC: For me, one of the best parts of the experience of writing Guilt By Association was if i didn’t have enough evidence, I could back up and add more. “Backspace, backspace, backspace… and we found a fingerprint, a fiber, DNA!” I could make a case as strong or weak as I wanted to.”

SR: There’s no doubt about that. When you’re writing stories about the Latin American underworld or terrorism, you’re so careful about what you can and can’t say. You might be using a document that tells the truth to a certain point, but then you have to limit yourself from making the connection. When you’re writing a novel, it’s good to apply those rigors, but then you say, “Hey, wait a minute, I’m in charge here!” It’s a good exercise to make it as realistic as possible, but there is the fun of having that creative control over how the action is going to unfold. I think both of us went through that.

MC: I think that’s where Sebastian and I come from the same place. We’ve both been limited by the truth and what can be proven in the past. But with a novel, you can say the things you suspect or even know, but can’t necessarily prove. But the experience of having been a prosecutor or a journalist makes you write fiction that’s logical; you build a case on the page that makes sense based on what you know could have been proven in a courtroom.Yes, you have the freedom from restrictions but you don’t want to stray so far that it becomes insane.

SR: When I was writing, I would think, “How would this scene happen based on things I know about an interrogation or an arms deal?” All of it is grounded in past experience and knowledge. That part of it was a lot of fun. There are a couple of scenes in the novel that are inspired by secrets, things I was told that I believed to be true, but I was not able to get quite enough sourcing to write in a newspaper story. But in the novel, I did end up using them to at least inspire moments.

MC: Yeah, that’s cool, that ability to write what you believed even if you couldn’t prove it is really liberating. The other cool thing is to be able to have fun. The world is hard; life is hard. I want to have a good time and I want my reader to have fun. If there’s one thing that was absolutely true in the DA’s office it was that there was plenty of punking each other, plenty of put-down-y banter. It made for a lot of camaraderie. It was very necessary in the midst of the miserable crimes we were dealing with. Making my book fun and helping people get away from life--this was a great opportunity to do that and lighten things up a little bit.

Sebastian, did you find your life as a journalist affecting your novel in any unexpected ways?

SR: There is a mysterious process I experienced; it feels like subconsciously you’re working on the novel even when you’re not. When you sit down [to work on your novel] and your plot has evolved--it’s like it was gathering steam in your head. Maybe because you’re so active and your mind is working intensely, something is going on where the creative process continues to work even if you’re not focused on it.

MC: I totally agree. There were times I’d look back at what I’d written and realize, “that came from ‘this case’ or ‘that case.’” You’re not even aware of it. It’s interesting to realize after the fact, how your former job affected your writing.

SR: It’s a mosaic of impressions. It comes together in a way that’s not always very direct, but that’s what creativity is all about.

MC: Good point. It always seems to happen somehow on this kind of subconscious angle. Things come through essentially, not literally. I hope it enriches the writing and makes it more real. It does to me, anyway.

SR: Absolutely.