Staff stumbled across Joseph Schexnider's corpse as they carried out renovation work. He went missing in January 1984 ahead of a court appearance for possessing a stolen vehicle, KATC-TV reported today.
Police investigating the grim find in Abbeville, west of New Orleans, have ruled out foul play.
They say Schexnider probably died from dehydration and starvation after climbing into the Bank of Abbeville's chimney and becoming trapped.
But why he was there remains something of a mystery.