Dementia 13

From Wikipedia:

Dementia 13 is a 1963 horror thriller released by American International Pictures, starring William Campbell, Patrick Magee, and Luana Anders. The film was written and directed by Francis Ford Coppola and produced by Roger Corman. Although Coppola had been involved in at least two nudie films previously, Dementia 13 served as his first mainstream, "legitimate" directorial effort. The plot follows a scheming young woman who, after having inadvertently caused the heart attack death of her husband, attempts to have herself written into her rich mother-in-law's will. She pays a surprise visit to her late husband's family castle in Ireland, but her plans become permanently interrupted by an axe-wielding lunatic who begins to stalk and murderously hack away at members of the family.

Corman offered Coppola the chance to direct a low-budget horror movie in Ireland with funds left over from Corman's recently completed The Young Racers, on which Coppola had worked as a sound technician. The producer wanted a cheap Psycho-copy, complete with gothic atmosphere and brutal killings, and Coppola quickly wrote a screenplay in accordance with Corman's requirements. Although he was given total directorial freedom during production, Coppola found himself fighting with Corman after the film was completed. The producer declared the movie unreleasable and demanded several changes be made. Corman eventually brought in another director, Jack Hill, to film additional sequences.