Right behind you / Lisa Gardner.

"Eight years ago, Sharlah May Nash's older brother beat their drunken father to death with a baseball bat in order to save both of their lives. Now thirteen years old, Sharlah has finally moved on. About to be adopted by retired FBI profiler Pierce Quincy and his partner, Rainie Conner, Sharlah loves one thing best about her new family: They are all experts on monsters. Is he a killer? Then the call comes in. A double murder at a local gas station, followed by reports of an armed suspect shooting his way through the wilds of Oregon. As Quincy and Rainie race to assist, they are forced to confront mounting evidence: The shooter may very well be Sharlah's older brother, Telly Ray Nash, and it appears his killing spree has only just begun. All she knows for sure: He's back."-