Bad medicine / Aimée & David Thurlo.

Enhanced descriptions from Syndetics:

Set on the Navajo reservation packed with Native American wisdom, Aimee and David Thurlo's Ella Clah novels are written with a sharp eye for conflict between the traditionalist and modernist ways of life. Former FBI Agent Ella Clah is now a special investigator with the native police force on the Navajo reservation. Ella's brother Clifford, a Hataali or medicine man, says that her investigative skills are gifts from the spirits who guard and guide the Navajo, but Ella insists it's her FBI training that has honed her instincts.When the daughter of Senator Yellowhair is killed in a suspicious car accident, the Senator accuses Ella and the tribe's medical examiner, Dr. Carolyn Roanhorse, of tampering with evidence and falsifying the autopsy results. An outbreak of meningitis leads to more trouble when many of those who are vaccinated begin dying from an unknown disease. Riots between Indian and White workers at the Navajo-owned mine stretch the resources of the tribal police even thinner.Convinced that solving one mystery means solving them all, Ella plunges into her investigations despite threats from all sides and her suspicions that Navajo witches are somehow involved. Ella Clah has sworn to protect her people from all menaces--spiritual and physical--and she's not going to back off now.