This is book 5 of the "Mac McRyan" series.

This note does not contain major spoilers for the book.

Mac and Sally are living in Washington. So Mac gets drawn into an investigation there.

This means his guns are completely illegal, federal felony level, much of the time, by the way; hate it when this kind of detail gets omitted! Would a former cop, working with an unfamiliar police department and the FBI, really ignore that? Would the other LEOs?

Can't help remembering Lucas Davenport's brief sojourn in New York in Silent Prey. This one does seem to be longer-term.

So there's a serial killer, leaving biblical verses behind like they do.

I'm feeling like the editing of these books is falling off; I noticed they were self-published before I read them, so I don't know if that's confirmation bias or not, though. For that matter, I know one can pay somebody to edit your book without going through a traditional publisher (even some of the same people).