The Lost, finale to The Bird with the Crystal Plummage...

This climax to the mystery, with strong sado-masochistic elements, has the knife-wielding Monica teasing Sam as she prepares to kill him. As she raises her knife, the police burst in and apprehend her, notified by Giulia, who had escaped. Sam is freed and Monica is taken to a psychiatric hospital. The victim of a traumatic attack ten years before, seeing the painting of the murdered girl drove her mad, causing her to identify not with the victim but with the assailant. Alberto likewise suffered from an induced psychosis, helping her to cover up the murders and committing some himself. Sam and Giulia are re-united and return to America - The Bird with the Crystal Plumage.

This film packs a wallop on this subject.  Did a little research and found The Bird with the Crystal Plumage which I have never seen.  I thought it was about Carlos Scalzi.   With some horror film style and technical videography, which I would have left out, the story is captivating right to the end, which has a twist sure to astonish.   Pieces of this  drama are also found in Artificial Intelligence and Valachi Papers.  Great acting.