From the archives of the Chicago Tribune: A diver recovers a Thompson submachine gun from the Calumet-Saganashkee Channel in a photo that ran in the paper on Saturday, Aug. 6, 1949. The story that accompanied the photo reported the investigation of a holdup that led to the deaths of two guards in the course of a bank robbery. “Two revolvers taken from the slain guards had been recovered with magnets from the same spot Thursday,” the paper reported, “together with cartridges and two machine gun clips.” Three of the robbers were nabbed after a fourth named names; one of these identified the machine gun as the one used in the course of the crime.
Looks like a nice M1A1 GI Thompson from WWII of course, rather than a shotgun.
This image reminds me of Papa Hemingway and his predilection to hunt sharks (and U-boats) with his own Colt 1921 Tommy Gun.