Una farfalla con le ali insanguinate

During pre-production, the film was promoted as an adaptation of an Edgar Wallace story. Less then two weeks before principal photography, the West German companies Rialto Film and Constantine Film (who were co-producing the movie) pulled out for unknown reasons, and any reference to Wallace was removed from the final film. The German connection is still reflected via Günther Stoll and Wolfgang Preiss, both stars of Rialto's Wallace adaptations (better known as 'krimi' films).

In the scene immediately following the credits, a woman with a couple of children playing in a park expresses concern that it's about to rain, pleading with the children repeatedly to stop their games and return home with her at once. A corpse rolls down in the bushes and the children turn around, only to see that the woman responsible for them has abandoned them, left in their dangerous circumstances, to run for the police.

Featured in Mad Dog Helmut (2016)