Classic TV - One Step Beyond - "Image Of Death" (1959)

An inspector is suspicious about the death of the wife of a Marquis, who, in fact, did kill her with his lover Charlotte as his accomplice. The Marquis becomes increasingly haunted by a stain on the wall which seems to be the image of his dead wife's face. He is ultimately tried and executed, but for the murder of Charlotte who has been literally scared to death by the stain.
https://www.imdb.com/title/tt0507789/plotsummary?ref_=tt_ov_pl

This video is in the Public Domain.