Blood Mania
Blood Mania is a 1970 film written by Peter Carpenter who also stars as Dr. Cooper and Tony Crechales and directed by Robert Vincent ONeil.
Returning to the house, Dr. Cooper embraces Victoria just as she sees an apparition of Gails corpse standing behind the door. It fades, revealing Dr. Coopers blackmailer, grinning menacingly as the painting is revealed, showing Dr. Cooper with a skeleton draped across his arms.
Source: Wikipedia