Extreme Instinct — Robert W. Walker

In novels such as KILLER INSTINCT and DARKEST INSTINCT, FBI pathologist Dr. Jessica Coran has probed the deepest recesses of the criminal mind, coming face-to-face with killers as brilliant as they are vicious. But now Jessica must face a deadly new foe. A murderer terrorizing the American West from Arizona to Montana who ties his victims down, drowns their sins in gasoline, and cleanses them with flame. He is on a Satanic mission - and only by stepping into the fire can Jessica stop him. (This book is sixth in Robert W. Walker's Instinct series.)