Some great formal ideas by H to hidde the silly premise: the asshole bourgeois paying for his original sin against the holy psycho. Chabrol did this several times better, with a healthy dose of humour and pulp!!
Cache ma peine
Elle est de n’être rien
Et de vivre
This one is the most "generic" invention of Vecchiali, a film with too many fathers (Hitch, Fleischer, the "Giallo", Clouzot/Chabrol) and without sons.
If the "giallo" appears as the framework from the very beginning, the easy solution for the public and the killer soon falls apart: the killer losing his will, the cop his reason, the plot his consistency, while the victims doubt between life or destiny,…