The Bloodstained Butterfly

• Composer Gianni Ferrio scored the film with a jazzy, orchestral sound unusually light for a giallo, matching the movie's courtroom-drama register more than its knife-work.
• Much of the runtime is spent inside the courtroom rather than following a cop's investigation — critics have called it closer to a courtroom drama with a giallo dusting than a traditional slasher-mystery.
• Director Duccio Tessari cast his real-life wife, actress Lorella De Luca, as Marta Clerici, Alessandro Marchi's mistress, whose testimony without her glasses on becomes a key courtroom sticking point.
• The film was shot largely in the medieval Italian city of Bergamo, using its narrow streets and public squares rather than studio backlots.
• For its 1972 West German release, distributor Warner-Columbia retitled it as an entry in the popular Edgar Wallace krimi series ("Edgar Wallace: Das Geheimnis der schwarzen Rose"), despite having nothing to do with Wallace's work — a common trick used to sell Italian gialli to German audiences at the time.

Marchi and Giorgio work as mirror opposites of guilt: one man buries a real crime under a TV star's respectability, the other buries real grief under vigilante theater — and Tessari never lets either of them look heroic, which reads as a dig at the genre's habit of romanticizing the 'wronged man who acts.'

The courtroom scenes that bookend the film aren't filler — they're the real argument: a witness without her glasses, mud explained away by a lucky excuse, a wrongful conviction that turns out to be right for the wrong reasons. Tessari seems more interested in how casually the legal system nearly clears a killer than in the killer himself.

Giorgio's copycat murders can be read as a broken kind of justice rather than pure revenge — he's not protecting Sarah's family, he's using his access to it to get close enough to force Marchi's confession, which makes the 'masochistic' relationship with Sarah less a romance than a means to an end.

TV sportscaster Alessandro Marchi stands trial for the brutal park murder of a young Frenchwoman, Françoise Pigaut — her body found by two kids in yellow raincoats as a storm rolls in. The case against him is built on shaky ground: an eyewitness who wasn't wearing her glasses, mud on his coat explained away as a splash from a passing car. While the courtroom chews over his guilt, his daughter Sarah is caught up in a masochistic relationship with the anarchic playboy Giorgio — who turns out to be Françoise's real lover. A second wave of killings starts, and Tessari's script slow-walks toward an ugly reveal: Marchi actually did it, and Giorgio has spent the whole film staging copycat murders as vigilante theater to force the truth into the open. It ends in a gunshot and a knife in an abandoned building, with Giorgio dying satisfied his frame-the-frame plan worked. The butterfly isn't a symbol of beauty — it's what's left after something delicate gets pinned down and dissected.