I am writing a mystery as closely aligned with the Golden Age of Detective fiction as possible, which is to say I'm putting emphasis on the fairness of the game. Back then, authors didn't bother with character development, choosing instead to focus on the plot, which eventually led to the decline of Detective fiction. Hardboiled detective novels, such as the ones written by Raymond Chandler, have room for development, but that is not the type of novel I want to write. My problem can be summarized thusly: A novel nowadays cannot expect to have no character development. However, to ensure that the reader has a fighting chance at solving the crime, the detective must be somewhat of a walking deus ex machina. I am not sure how to develop a character while still making him the omnipotent figure the reader may rely on to help him solve the mystery. What do people think about this issue?