Marcia Clark on how her new book is different than the old Marcia, Marcia, Marcia

Famous as lead prosecutor in the murder trial of O.J. Simpson, Marcia Clark still works as a lawyer, but she’s also an author. First came 1997’s “Without a Doubt,” a memoir of the case, and more recently, a series of legal thrillers. Clark’s first four novels starred the same main character, Rachel Knight. Like Clark, Knight was a prosecutor in the Los Angeles district attorney’s office, an ambitious, hard-charging lawyer who took her job very seriously.

“I wanted to do something different,” says Clark during a phone interview about her next book. “I was a defense attorney before I was a prosecutor, and I’m doing defense work again now. So I wanted to write a character who was a little more wild and woolly than Rachel.”

Clark’s new crime novel, “Blood Defense” — the first in a planned series published by Thomas & Mercer, to be published May 1 — centers on defense attorney Samantha Brinkman. Unlike Rachel Knight, she’s more than willing to bend the rules to get what she wants. “I wanted to write a more morally ambiguous character,” Clark says. “It’s freeing, it’s more fun.”

Clark’s persona during the O.J. Simpson trial was buttoned up, even severe. But public perception of her has changed with the television series “American Crime Story: The People v. O.J. Simpson,” particularly the episode “Marcia, Marcia, Marcia,” which portrayed Clark’s struggles in the spotlight in a newly sympathetic light.

As a lawyer who’s worked on both sides of the criminal bench, Clark is acutely aware of the different roles each must play.

“Both sides have their restrictions and their boundaries,” she says. “They’re different, and the pressures are different. When I went to the prosecutor’s office, I wanted to be one of the good guys that the defense could trust. I’d try fair clean cases, pull no punches, no below-the-belt stuff. Honorable. Because that’s the kind of prosecutor I wanted to deal with.”

With her new main character, Clark says, “I was channeling the defense perspective of things — well, not all defense attorneys, but some. Samantha hates all cops. She’s an extreme character.

“You have a lot more leeway with a defense attorney than with a prosecutor. I wanted to swing for the fences a little more, incorporate more of my experience as a lawyer.”

Trial lawyers are storytellers — perhaps that’s why legal thrillers are perpetually popular reading and why so many of their authors have worked in the courtroom. The narrative responsibilities differ depending on what side of the bench you’re on too.

“The prosecution has to go with the evidence and the facts and tell the story as it happened,” Clark says. “The defense has more creative freedom. All you have to do is look for a defense that works. But it doesn’t have to be the truth. Sometimes you get lucky and it is, but sometimes you don’t, and either way it doesn’t matter. You’re there to defend the client, and that’s your job.”

The popularity of FX’s series “The People v. O.J. Simpson” has renewed interest in the mid-’90s trial that thrust Clark into public life and found Simpson not guilty. She gives it a positive review, mostly.

“I think it’s really good, to be honest,” she says. “I was really pleasantly surprised at how well they handled the bigger issues, super-impressed with the performances; the actors are just phenomenal.”

That doesn’t mean watching the show has been easy.

“It’s weird,” Clark says. “It’s a little out of body. I always make sure I have friends around, because it’s a little more grounding.

“And it’s also very painful, to be honest with you. I’m reliving something that was a very horrible time in my life.” More than that, Clark says, she worries that the case’s entertainment value obscures the tragedy at the trial’s heart. “I know that this is a great series and I know it’s talking about big issues, but please remember at what a cost. Please remember two people were brutally murdered, innocent people.”

Nicole Brown Simpson and Ronald Goldman, Clark says, are always in her thoughts. She dedicated her book about the trial, republished as an ebook this year, to them. And she worries about the pain their families must feel as the case once again occupies the public imagination.

“If it’s painful for me, how must it be for them?” she says. “I think about them every day.”

Tabloid attacks and intense media interest in Clark’s appearance during the trial are persistent themes in the series. Sarah Paulson portrays Clark as alternately wounded by and contemptuous of the insults. As Clark recalls those days, she dryly remarks that the scathing media attention wasn’t her top priority.

“I was more concerned, far more concerned, with what was going on inside the courtroom, which was bad enough,” she says. “And you know, people are always going to scrutinize women in general when they go out in public, any time they present themselves. There’s no safe corner for any of us, the minute we get out on television. I just think it goes with the territory.”

Berkeley-born Clark was a tomboy growing up, a tough girl more focused on observing life than fussing over her appearance. An early obsession was crime.

“I have been addicted to crime since I was born,” she says. “I was making up crime stories when I was a 4- or 5-year-old kid.” Meanwhile, she was reading crime and mystery books, starting with “Nancy Drew, and the Hardy Boys, all that,” she says.

Clark laughs and says she had always thought writers had it easy “because they can be very successful, but no one knows what they look like. You don’t get recognized. It’s a pretty cool way to work.”

Her Rachel Knight series was published by Mulholland Books, a traditional publisher. Working now with Amazon, she says, has been “a real pleasure.” The pace would sound punishing to many writers — two books a year. “Blood Defense” comes out May 1, and the second one, already written, will be released in November. But Clark says the workload suits her.

“I kind of like to write fast. It keeps the pacing up,” Clark says with another chuckle. “And it keeps me off the streets.”

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‘Crime Fiction: The Long Arm of the Law’

Who: Moderator, Scott O’Connor, with Marcia Clark, Lee Goldberg and T. Jefferson Parker

Where: Los Angeles Times Festival of Books, USC, Andrus Gerontology Center, 3715 McClintock Ave., Los Angeles

When: 1 p.m. Saturday, April 9

Info: events.latimes.com/festivalofbooks

Tuttle is a book critic and freelance writer whose work appears regularly in the Boston Globe.

Clark will appear at the Los Angeles Times Festival of Books on April 9.