Directed by Riccardo Freda, Double Face (1969) merges the sensual paranoia of Italian Giallo with the cool precision of the German Krimi.
When a wealthy businessman suspects his wifes murder is part of a twisted conspiracy, his investigation spirals into deception, obsession, and psychological tension a stylish precursor to 1970s Euro-thrillers.

Arrow Films

In the post-war years, the proliferation of transnational European co-productions gave rise to a cross-pollination of genres, with the same films sold in different markets as belonging to different movements. Among these, Riccardo Freda (I vampiri, The Horrible Dr. Hichock)s Double Face was marketed in West Germany as an Edgar Wallace krimi, while in Italy it was sold as a giallo in the tradition of Mario Bavas Blood and Black Lace, combining elements from both genres for a unique and unforgettable viewing experience.

When wealthy businessman John Alexander (the legendary Klaus Kinski, giving an atypically restrained performance)s unfaithful wife Helen (Margaret Lee, Circus of Fear) dies in a car crash, it initially looks like a freak accident. However, the plot thickens when evidence arises suggesting that the car was tampered with prior to the crash. And Johns entire perception of reality is thrown into doubt when he discovers a recently-shot pornographic movie which appears to feature Helen suggesting that she is in fact alive and playing an elaborate mind game on him…

Psychological, psychedelic, and at times just plain psychotic, Double Face stands as one of the most engaging and enjoyable films in Fredas lengthy and diverse career a densely-plotted, visually-stunning giallo that evokes much of the same ambience of paranoia and decadence as such classics of the genre as One on Top of the Other and A Lizard in a Womans Skin.

Från IMDB:
After a businessmans unfaithful wife is seemingly killed in a car acc