George "Machin Gun Kelly" Barnes
Crime: Kidnapped oil tycoon and held him for ransom.
Collected $200,000 and was famous for using a machine gun.
Story: Who is responsible for the kidnapping of Charles Urschel.
Sources: newsok.com, fbi.gov, crimelibrary.com
Evidence: Urschel left a lot of evidence behind that helped the investigators in their investigation.
Suspects: All major gangs of America in that time.