It's not always easy to empathise with the alleged heroes in giallo films. Take Enrico - he's a married teacher, and he's first scene trying to have sex with the student with whom he's having an affair. When she's distracted by what appears to be a murder taking place, he gets angry. That's your central character, folks!
We're so preoccupied with Enrico (Fabio Testi)and his wife Herta (Karin Baal), and the subsequent murders of course, that it escapes our notice that the titular character Solange does not make an appearance until a large proportion of the film has taken place.
Giallo films - described by Wikipedia as '‘20th-century Italian slasher genre of literature and film, usually with mystery elements and often with either supernatural horror or crime fiction elements’ - is a fairly broad and far-reaching genre, usually involving a killer dressed in black wielding a serrated knife or somesuch. There's a lot more to that set-up here, and at the centre of it, a grim and upsetting story.