In Daniel Friedman’s second Buck Schatz mystery, Don’t Ever Look Back, the 87-year-old former Memphis, Tenn., cop shows his age.

Where did Buck Schatz come from?

Buck is based partly on my grandfather, Buddy Friedman, who died in October 2013 at the age of 97, and also on a great aunt, Rose Burson, who lived in a dementia ward in an assisted-living facility for 10 years before dying at 88. Buck’s habit of insisting on smoking in places where people tell him he can’t was one of my father’s tics. The crime novel aspect came from trying to imagine what mid-20th-century action heroes like Dirty Harry or Donald Westlake’s Parker might be like today, as extremely old men.

Why make him 87?

There are a lot of mystery novels that feature retirees or older characters in their 60s or 70s—characters who use their wisdom, cunning, and, in some cases, physical force to handle the problems their plots throw at them. A big theme of these stories is how these older characters can do everything younger characters can do, and sometimes more. For example, there’s the inspector who was pushed into mandatory retirement at 65, against his will, and is called back into the field when a knotty case stumps his former agency. This is a positive message, and there’s a lot of truth to it. But those stories don’t depict the realities faced by my grandfather, who died a few months ago, and my grandmother, Margaret Friedman, who is 96. They were also fit, active seniors for as long as it was physically possible, but when you reach a certain age, your body starts to fail you in frustrating ways. This is an experience that is rarely explored in fiction, and it’s the kind of struggle I’m trying to write about.

What effect did your father’s murder have on your fiction?

My life was turned upside down by crime. That’s the specific, unique perspective I bring to the genre, and that’s the subject matter I’m interested in exploring. I’m trying to get to a moment that is very raw and emotional, and that means every story I tell about Buck, or about any character I write, has got to be personal for them.

Given Schatz’s age and mental issues, do you have an end in mind for the series?

I do. I think the Buck Schatz series is about how, near the end of this man’s life, his past sort of bubbles back up on him, and, by seeing him address or refuse to address these different unresolved problems, we learn who he is. When that well of material is exhausted, the series is done.