Rider On The Rain (1970)
aka's: Le Passager De La Pluie/L'uomo Venuto Dalla Pioggia/Rain
A beautiful young woman (Marlène Jobert) in the South of France is stalked and raped by a mysterious masked assailant. She shoots him dead soon afterwards and dumps his corpse in the sea. Later, an American investigator (Charles Bronson) turns up, and to her horror he seems to know everything about what she has done. Also with Gabriele Tinti, Jean Gaven and Jill Ireland (Bronson's real-life wife).
Comes from a very nice widescreen import print.