Stuart Whitman was considered for the lead role.
Tony Curtis broke his nose while filming a chase scene.
Tony Curtis does not appear until one hour into the film.
Lionel Newman's original music consists of one cue ("Peter the Pole") lasting 22 seconds.
20th Century Fox originally hired Terence Rattigan to write the screenplay based on the book by Gerold Frank, but he wrote it as a comedy and was replaced by Edward Anhalt. In Rattigan's version, the killer was revealed, by a computer, to be Darryl F. Zanuck.
Film debut of Edward Winter.
Her role as Edna became the final film role for Enid Markey, ending a career of almost 60 years.
Shortly before filming was set to begin the real Albert DeSalvo escaped from the mental institution where he was imprisoned. He was later captured after being on the run for 33 hours.