You were a single mother selling life insurance when you created J.P. Beaumont in Until Proven Guilty, which was published in 1985. Where did he come from?

I usually say I met him on a train. I'd spent about six months trying to write a book, and I couldn't make it tell its story. In the spring of 1983, I was on a train trip and I suddenly thought I might write the story through the eyes of the detective. He just popped into my head. I wrote 30,000 words in six weeks.

This is the Beaumont series' 20th anniversary. What's the secret to his popularity?

I think people like him because he seems like a regular person, with little glitches and hitches. He has an old leather recliner that's the height of dis-fashion. He's like an old dog you really know well and you've accommodated yourself to his peculiarities.

Why did you switch Beaumont from the Seattle police department to the Washington State Special Homicide Investigation Team?

One of the reasons is that it loosens up the jurisdictional boundaries. It gives him freedom of movement; he's not confined to Seattle.

Does the budding romance with Melissa Soames in Long Time Gone forecast a turn for the better in Beaumont's life?

I've been getting a lot of e-mails saying isn't it time that Beaumont gets lucky. Melissa does have his grandmother's seal of approval, which is a step in the right direction. That's the thing about writing a series. You get a whole group of characters in the background. In Long Time Gone, I put Ron Peters' kids in the foreground. The readers who've been dealing with them since they were little girls will see what they're doing now. They'll also see that being a parent is a crap shoot.

How much research did you do for this new book to give the wonderful feel for Seattle in the 1950s?

Quite a bit; it was fun dealing with Seattle history. The trick with research is to do enough to make it work, without becoming a researcher. You don't need to know everything or else you don't write the book.

This is your 30th book, the 16th Beaumont. Did you ever think you'd write so many?

When I wrote that first Beaumont 20 years ago I thought I was writing a stand-alone until the publisher bought it as a series. Now I know I'm doing what I always wanted to do.

As a mystery author, do you ever feel patronized?

One of the challenges is the people who pat me on the head and tell me they don't read murder mysteries. When I ask them what they read, it's usually a book that contains a mystery.