Snuff

Snuff is a 1976 splatter film directed by Michael Findlay and Horacio Fredriksson. Originally an exploitation film loosely based on the 1969 murders committed by the Manson Family, it is most notorious for being falsely marketed as if it were an actual snuff film. The controversy about the film was deliberately manufactured to attract publicity: it prompted an investigation by the New York County District Attorney, who determined that the murder shown in the film was fake. This picture contributed to the urban legend of snuff films, although the concept did not originate with it.

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.

Poster © the film's rights holders.