Cops, criminals and neglected families collide with disastrous results in Person of Interest, the third novel from Theresa Schwegel, whose debut, Officer Down, won the Edgar Award for best first novel.

How did you come to write about police officers?

I wrote Officer Down because a friend was having an affair with a married cop. I didn’t know anything about police work—I was more interested in why a woman with so much to offer would give it to someone who was ruining her. The cop characters—my supposed heroes—are also true to dramatic form: pushed to the edge, soul divided, strong and sad.

How does your background in film influence your work?

In screenwriting, if it’s not part of the plot, it’s not on the page. Movie dialogue is written so the actors do the work: they want to say a lot with a little. When I write fiction, I try to make each scene concise and action propelled. After the scene is there, I add those things a screenwriter leaves up to the filmmakers: the costumes, props, tone and color.

Samantha Mack was such a flawed but endearing hero in Officer Down. Why did you choose not to bring her back?

I did quite a bit of damage to Samantha in Officer Down, and I didn’t really want to write the recovery. I’m happy to be doing stand-alones, because I’m interested in exploring the way a character with certain flaws overcomes a destructive situation (or doesn’t). I’d rather write about the experience than what comes from it on down the road.

Corruption figures heavily in your work. Was this a conscious choice of theme?

I hadn’t planned to focus on corruption—in fact, after I wrote my second novel, Probable Cause, I felt a little guilty because I’d had so much candid input from upstanding, honest cops and I’d gone through round two, making them look bad. I think corruption makes for good storytelling because it keeps the enemy close. It makes the crime personal.

In Person of Interest, why did you decide to focus on the deteriorating marriage of the McHughs?

I wrote about the McHughs’ crumbling marriage because I wanted to know how suppressing all that emotion, over time, weighed on personal relationships. I wanted to know what happened when it all came crashing down.

What’s next for you?

I’m working on my fourth book, and I’m bringing back Sloane Pearson, the detective from Probable Cause. She’s moved from homicide to sex crimes and is working on a serial rape case.