Of the 1545 men who did time
on Alcatraz, only a handful were notorious-among them, Al "Scarface" Capone,
"Doc" Barker, Alvin "Creepy" Karpis, George "Machine Gun" Kelly, Floyd
Hamilton, and Robert Stroud, the "Birdman
of Alcatraz" (who actually conducted his famous bird studies when
he was imprisoned at Leavenworth). Most of the inmates were men who had
to be problems in other prisons populations-escape risks and troublemakers.