Suspicious Behavior by L.A. Witt , Cari Z.

Detective Darren Corliss is hanging by a thread. In between recovering from a near-fatal wound and returning to work at a hostile precinct, he’s struggling to help care for his ailing brother. His partner and boyfriend, Detective Andreas Ruffner, wants to help, but doesn’t know how. And with his own family crises brewing, Andreas is spread almost as thin as Darren.

For cops, though, life takes a backseat to the job. When a stack of unsolved homicides drops into their laps, Andreas and Darren think they’re unrelated cold cases. But when a connection surfaces, they find themselves on the tail of a prolific serial killer who’s about to strike again.

Except they’ve got nothing. No leads. No suspects. Just a pile of circumstantial evidence and a whole lot of hunches. Time is running out to stop the next murder—and to pull themselves back from their breaking points.