Red Rings Of Fear - 1978 - 6/10
AKA - Enigma Rosso

Saint Theresa’s boarding school. For girls, a dangerous place.
One has seemingly been raped to death. Her three best friends keep silent.
The detective tries to break down the girls, school administration, teachers.
As he digs deeper, events grow more lethal.
Story is sleaze, but focus is on Inspector Di Salvo, and his deteriorating relationship with his casual girlfriend.
Procedural process dominates over the usual Giallo flourishes. Even colors seem toned down.