Who did the glass key murders?

The Glass Key murders refer to a series of fictional crimes in Dashiell Hammett's 1931 novel "The Glass Key." In the story, the protagonist, Ned Beaumont, investigates the murder of a political figure and becomes entangled in a web of crime and betrayal. The true murderer is revealed to be a character named Paul Madvig, who is involved in the corrupt underworld of the city. The novel explores themes of loyalty, betrayal, and the moral ambiguity of its characters.