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: And so I have learned over the years a little bit about DNA. Although, I have to confess, every time I get involved with DNA, the science has evolved so quickly, it's as if I was starting again. But I have had a recent pro bono case that involved just a few of the features that end up being central to "Identical." But I did do a lot of research and I had a lot of friends - my friend Julie Segre at NIH of the Human Genome Project there, and Lori Andrews is a great law professor and genetics expert in Chicago.

: And you just know how much to put in? I would imagine the temptation, once you've learned the intricacies of one kind of scientific process, how do you discipline yourself to know when is too much?

: Generally, the comments of the early readers help tame my impulse to try to teach everybody else as much as I've learned.

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: So a long-time buddy of mine from the U.S. Attorney's office in Chicago Julian Solotorovsky; and Julian drew a big X...

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: ...through the first draft and, you know, wrote in his usual terse way: Too much. And, you know, that's always the hazard of research. I did, you know, a panel the other night in New Haven and there were four novelists there. And we were all talking about the problem of research - namely, you know, once you've learned about something it's very, very hard not to try to impart everything you suddenly know.

: Another theme woven through this story is about coming to grips with the passing of time and aging. This is especially true for the character Tim, who is an investigator in the story.

: Mm-hmm. Mm-hmm.

: Can you tell us a little about him?

: Well, Tim Brody is an old homicide detective who in fact, was the - lead the investigation into Dita's murder 30 or 25 years before. And he's 81 years old now, still doing odd jobs for the Kronon family. And, you know, there's always the character who runs away with the book - if you're lucky and the book comes to life - and Tim was that character for me. I just became totally beguiled with him. He's old. He knows he does not have all that much time left. He's of very sound mind and not completely...

: But he thinks he's kind of slipping. He's afraid.

: Yeah. Yeah, he knows that age has got its grip on him. What I adored about him is that he's had his share of blows, but he's generally affirmative about people. At one point, somebody remembers a conversation with Tim in which he explains what he was doing as a homicide cop, which was helping the rest of us be good, by showing us what happens if we don't mind our Ps and Qs; that he was trying to help everybody live a better life, in his own view.

: So, you have done well. You have written best-sellers - several have been turned into movies. You could choose not to practice law, I imagine.

: You know, I think the truth, it just seemed kind of naturally interesting to me, the law, and it still does. You know, I will still get lost in reading court decisions and musing about, you know, the rationale for that, and trying to line that up against other things I know. And I enjoy the company of lawyers also, I have to admit, even though, you know, they're the butt of constant jokes. And between the two things, liking the law and liking lawyers, it's sort of natural to continue.

: Scott Turow. His newest book, a novel, is called "Identical." He spoke to us from the studios of New England Public Radio in Amherst, Massachusetts. Thanks so much for talking with us, Scott.

: Thank you, Rachel. Transcript provided by NPR, Copyright NPR.