The Hunt for Mel's Gold - Dixie Jo Jarchow - Bog

All her life, Tes has lived in the shadow of her brilliant, charismatic brother, but the novelty of having a serial killer in the family has long worn off. All she wants is answers: Why did he butcher five people? Was there anything she could have done to stop him?
When she discovers that he has escaped from the state hospital and may be coming for her, she takes the first opportunity to leave town. An enigmatic Native American mercenary offers her a chance to renew her hunt for the fabled treasure of Mel's Hole several states away. She found it once years ago as a grad student but then her brother massacred five people and her life was derailed.
Tes sets off to give herself some breathing room while she figures out how to find out why her brother turned murderous without becoming her brother's next victim.