Murder in the Big House (1942)

When a prisoner on Death Row is "accidentally" killed just before his execution, a reporter smells something fishy. His investigation reveals that the condemned man was about to reveal some damaging information about the connection between the city's corrupt political machine and its major organized crime ring. The reporter hatches a plan, with the help of the paper's alcoholic political columnist, to get himself thrown in prison to get the information the murdered prisoner was going to reveal and expose both the crooked politicians and the gangsters they're in cahoots with.