One perfect shot : a Posadas County mystery
(Book)

"Book 18 in the Undersheriff Bill Gastner series" -- author's web site.

"When a county employee is found shot to death in sun-drenched daylight while sitting in his county road grader, Undersheriff Bill Gastner is faced with puzzling questions. The simplest explanation--that an errant bullet from a careless target shooter's rifle blew out Larry Zipoli's brains--is soon discarded as inconsistencies surface. The fatal bullet shows no rifling marks, and investigation reveals that the shooter walked directly toward the road grader, in full view of the victim--who did nothing to defend himself. In addition to the demands of the investigation, Gastner learns that Sheriff Eduardo Salcido has hired a new deputy without discussing the matter with his undersheriff. And Gastner learns that the new hire is destined to be the first female road patrol deputy in the history of Posadas County. Thus begins Gastner's relationship with Estelle Reyes, whose shrewd observations shed important light on a crime that rattles all kinds of skeletons lurking in Posadas County closets" -- from author's web site.