I find the idea of vigilante justice very attractive. I like the idea that the murderer decides that this person has gone too far, and nothing will happen to him unless she does something to stop him.

Brunetti embarks on a voyage of exploration in the often murky world both of opera and the victim's family eventually unearthing a surprising conclusion. What began as a red tape headache ends in murder when the bureaucrat is later found dead after a mysterious fall from a scaffold. Willful Behaviour (2002)
When one of his wife Paola's students comes to visit him with an interest in investigating the possibility of a pardon for a crime committed by her grandfather many years ago Commissario Brunetti thinks little of it beyond being intrigued and attracted by the girl's intelligence and moral seriousness.

The Commissario Brunetti novels are all situated in or around Venice. She stopped teaching and concentrated on writing and other cultural activities in the field of music (especially Baroque music).