Friends in High Places — Donna Leon

In Friends in High Places, Commissario Brunetti is visited by a young bureaucrat investigating the lack of official approval for the construction of Brunetti's apartment years before. What began as a red tape headache ends in murder when the bureaucrat is later found dead after a mysterious fall from a scaffold. Brunetti starts an investigation that will take him into the unfamiliar and dangerous areas of drug abuse and loan-sharking, and will reveal, once again, what a difference it makes in Venice to have friends in high places.