It was an Italian immigrant, who was trying to shoot Franklin D Roosevelt, but by accident hit the mayor (this happened in Florida if I correcctöy remember, both men were visiting the place). He had a rare (and maybe unknown) condition which made his stomach hurt terribly and caused more-than-usual flatulence. This combined with his poor English made him socially isolated, and he developed paranoia that FDR is responsible for this condition and therefore he tried to shoot the man. I believe he was later executed in electric chair.
I can't remember what the guy's name was though.