Unsub by Meg Gardiner

Unsub by Meg Gardiner - 571 pages

Caitlin Hendrix has been a Narcotics detective for six months when the killer at the heart of all her childhood nightmares reemerges: the Prophet. An UNSUB—what the FBI calls an unknown subject—the Prophet terrorized the Bay Area in the 1990s and nearly destroyed her father, the lead investigator on the case.

The Prophet’s cryptic messages and mind games drove Detective Mack Hendrix to the brink of madness, and Mack’s failure to solve the series of ritualized murders—eleven seemingly unconnected victims left with the ancient sign for Mercury etched into their flesh—was the final nail in the coffin for a once promising career.

Entertaining with twists.

Killer Instinct  by S. E. Green
288 pages

 This is a non-gory version of Dexter. Only, Lane is in high school and she doesn't kill her "victims", she apprehends them.