Former-prosecutor-turned-thriller-writer Linda Fairstein has set her newest book, “Killer Look,” in the fashion industry.

Out today from Dutton, the 400-page summer read is the 18th in the author’s series rooted in the life of Alex Cooper. Fairstein’s friend Hillary Clinton has publicized her fandom.

Having led the sex crimes unit of the Manhattan district attorney’s office from 1976 until 2002, Fairstein knows the criminal world better than most. Just at the beginning of her book tour — with a book signing at Barnes & Noble on the Upper East Side later today — the author talked about her careers past and present in an interview Monday. Most mornings start early with three cups of black coffee, a bit of e-mail distraction and then Fairstein gets to work in her Upper East Side home office or in her writer’s cottage on her Martha’s Vineyard property.

A two-hour lunch with Fern Mallis, a friend of 25 years, at Freds at Barneys New York helped to percolate the research for her latest book. “I always go in by saying, ‘Look, I’ve got to kill people and I need motives that might be real,'” she says. “No holds barred, Fern just lit up and I filled up one of those large Moleskine notebooks.”

Here, Fairstein discusses her writing, the fashion world — and Hillary.

WWD: The Costume Institute’s Met Ball comes into play. Have you ever been?

Linda Fairstein: [Laughs] I’m like a kid with her nose against the candy store window. I follow it closely as I did with this year’s gowns. I love it, but I’ve never been.

WWD: What did you find most unexpected about the fashion industry?

L.F.: The global impact and the size of the haute couture market — millions of dollars — with Muslim women was just a complete surprise to me. I did not know that Dolce & Gabbana and other companies were designing specifically for that market. They have to be covered in hijabs and yet they can have bling on their sandals and eyeglasses, and nothing else shows. That’s one of the things that put me in the direction of having my victim in “Killer Look” be a businessman and not a runway model as so many dressed-to-kill murder mysteries do. I wanted to get into the business end of the business.

WWD: Will you be hosting the Obamas at all when they vacation on Martha’s Vineyard or go to the Democratic National Convention?

L.F.: I won’t be hosting them. I’ve seen them every summer at somebody else’s. I know them and I admire them a lot so I will be seeing them on the Vineyard. I will not be going to the DNC. The Clintons will be coming to the Vineyard. There’s a fund-raiser there for the Clinton campaign on August 20. Twelve couples are cohosting at the Edgartown home of Carol and Frank Biondi [former head of Viacom and later at Universal Studios.] We are one of those.

WWD: Where do you live on the island?

L.F.: I’m in Chilmark. The Clintons started coming here in 1993. It’s been a real refuge for both of them. For me, I started coming here as a prosecutor. It is such a safe haven. I don’t mean to say from violence. You just get off the plane and it’s an oasis from all the emotionally charged work I did as a prosecutor. I look at people with much higher-stressed jobs than mine and campaigns like this, and I just think it’s an island that provides a lot of privacy and respect for privacy. It’s a happy place to be.

WWD: How do you deal with people who don’t know you personally but who may associate you with the Central Park 5 case or the Dominique Strauss-Kahn incident?

L.F.: I just wish they would learn the facts. I was not the prosecutor in the Central Park case. It was my unit and my friends who did it. There was a 12-year pretrial preparation for a civil trial in which the city, under Mayor Bloomberg, defended us vigorously. And this mayor [Bill de Blasio], a friend of Al Sharpton’s may I say, settled the case without ever meeting us, without ever knowing anything about it. At the same time he settled it for a huge amount of money [$40 million], he announced there had been no wrongdoing by police or prosecutors so I don’t know how he justifies spending the city’s money but he never bothered to tell me. But people don’t know facts. They don’t know what my role was or wasn’t.

WWD: And the other?

L.F.: [With] Strauss-Kahn I had nothing…I was long gone from the district attorney’s office. I commented. I did some talking-head work on the case. I had strong views about what the evidence was and wasn’t but it had nothing to do with me. Probably my highest profile case that the public does know was Robert Chambers, the so-called Preppy Murder case. Next month is the 30th anniversary of that murder [of 18-year-old Jennifer Levin in Central Park] so there is a lot of media interest in that. He did all 15 years that he was sentenced for manslaughter that he was convicted of. Then he got out and had a minor drug rap in [2005.] Then he was arrested for drug sales — having nothing to do with me, I was long gone — [and sentenced to 19 years in prison] from his girlfriend’s East 57th Street condo after undercover police were alerted to that by neighbors. Before he gets out after the two felony convictions, if he’s eligible for parole, it will be when he’s close to 70.

WWD: What do you have coming up?

L.F.: I’ve written my first book for 8 to 12 year olds called “Into The Lion’s Den” that comes out in November. Nancy Drew was the book series that launched me on both careers, when I was an adolescent. Obviously I am not trying to re-create Nancy Drew but this is my homage to the series. I have a 12-year-old kid sleuth Devlin Quick, whose mother is the first woman police commissioner in New York, which is the job I wanted in the Eighties. Through the mother’s job, Devlin gets access to the DNA lab and fingerprints and other things most 12-year-olds couldn’t do. The next Alex Cooper book is called “Deadfall” that picks up in the morgue an hour after “Killer Look” ends.

WWD: Would you still want to be police commissioner today?

L.F.: I’d need to be younger but it fascinates me. I’m laughing and I don’t mean to laugh at what the problems are, and I think have always been. It’s kind of shocking with the police shootings, and the executions of the police officers in Dallas. I just have such enormous respect for the men and women who do this job and how to get it right. It’s better that I’m doing what I’m doing now…I think most of these problems have always been there. It would be nice to think we’d solved race relations in this country but current events make me fearful that we haven’t.