What does the sleuth do for a living?

My most recent mystery "Sea-Born Women" by BJ Mountford has a woman "sleuth" who is really a restaurant owner/volunteer caretaker for the National Park Service. Another recent read has a sleuth that in "real life" was paid as genealogist who got involved in solving the murder. I just think that it is interesting, how all of these people get involved with murders/crimes and use skills from their "real life" to solve the murder before the police.