Hello
I've just found my grandfather's 1940 census and to my surprise it says he was in prison in 1940! Does anyone know how I can find out when and why he was in prison?

His name is John Del Monte, born 1899 in Italy, lived in Brooklyn Ny and in 1935 the state census says he lived at home (not in prison at that time) so some where between 1935 and 1940 he was arrested and sent to Rikers Island Prison located in The Bronx NY. YIKES! a little something mom forgot to mention. lol

Thanks to anyone who can help me.