Crimson, the Color of Blood
Las ratas no duermen de noche (original)
A mad doctor performs a head transplant on an injured criminal. The crook’s evil acts make him even more dangerous and murderous than before.
Starring Paul Naschy, Silvia Solar, Olivier Mathot, Evelyne Scott, Claude Boisson, Gilda Arancio, Pierre Biet, Víctor Israel, Richard Kolin, Antonia Lotito
Watch "Crimson, the Color of Blood" on Tubi TV released in 1976. It's a drama and horror movie, and has a rating of 4.3 out of 10 from Imdb which is fairly low for this kind of movie, and is currently available to watch for free.