House of Shadows, aka. La casa de las sombras (1976) starring Yvonne De Carlo, John Gavin, Leonor Manso

A young lady accidentally stumbles into an abandoned mansion and becomes a witness to a murder.  A murder that happened 23 years before.  First, it should be mentioned what this film is not it is not the more-famous House of Shadows with Peter Cushing. It also has no connection to the various Dark Shadows TV series or movies. It’s an Argentinian film; I watched the dubbed American version.