Factual error: The film begins in 1860, but the majority takes place 20 years later, so 1880. When James Rankin obtains files on the Haymarket Strangler/Edward Styles case we are shown another box labelled with details about Jack the Ripper, who wasn't active until 1888.
The Haunted Strangler (1958)
1 mistake
Directed by: Robert Day
Starring: Boris Karloff, Anthony Dawson, Jean Kent
James Rankin: I'm sorry, Barbara, but a man must do the work in which he believes.