Complex sentence: According to TCM's Robert Osborne, a sequel was planned for this film that would continue the mafia theme; but during the planning stage, famous aviator Charles Lindbergh's son was kidnapped and killed by gang members.
Split into simpler sentences: According to TCM's Robert Osborne, a sequel was planned for this film that would continue the mafia theme. However, during the planning stages for this next proposed film, famous aviator Charles Lindbergh's son was kidnapped and killed by gang members.