Kellerman’s psychologist sleuth, Alex Delaware, assists the LAPD in solving a particularly baffling crime in Night Moves (Ballantine, Feb.).

How did you get the idea of a corpse with its hands severed and face shotgun-blasted off being discovered in the home of a family that can’t account for its presence?

Ideas just fly into my head. Because I’m 68, I write everything down. There are currently 86 plotlines in my files, and this was one that stuck with me.

How has your training as a psychologist influenced your writing, and what were the advantages in making your lead a psychologist?

Before I began the Delaware series, I realized that what I did as a child clinical psychologist and med school professor was, essentially, detective work, and I’d like to think that my attention to detail combined with some understanding of personality has helped enrich the books. Since Delaware is a therapist, people talk to him, he’s a vehicle for drawing out information, as I was when I was in practice. There have been a couple of books—Silent Partner, Bad Love—where he’s the focus, but generally,

I see him as a modern-day Sherlock Holmes: brilliant, driven, hyperobservant, and tuned into the nuances of human behavior.

In what way has psychology changed since the mid-1980s, when you began the series?

A couple of years ago, I delivered the keynote address at the National Convention of the American Psychological Association. In that speech, I remarked how the tendency to psychologize nearly everything has replaced the old days, when mental health issues were taboo. Overall, it’s an improvement, but it does end up being a double-edged sword: everyone feels qualified to toss out diagnoses—ADHD, OCD, psychosis, you name it—carelessly, foolishly, and erroneously. These are disorders that require careful, professional evaluation.

Have those changes affected the series?

In the talk show age, bad behavior is often excused as a “disease.” Witness the nonsense labeled as “sexual addiction.” The psychologization of amorality and immorality allows lowlifes like Harvey Weinstein to check into an expensive “rehab” center under the guise of receiving treatment. Let’s bring back personal responsibility and notions of good and bad. Alex, on the other hand, hasn’t succumbed to inanity—he’s a well-trained, experienced, logical psychologist who sticks to the facts. One of the reasons I began the series is that psychology is rarely, if ever, depicted accurately in fiction, and, with few exceptions, that’s still the case.