Seven Blood-Stained Orchids(1972)

Original title: Sette orchidee macchiate di rosso

A maniac on the loose is committing savage acts of slaughter, and one survivor may be the only key to unmasking the serial slayer known as the Half-Moon Killer. The mysterious half-moon lockets he leaves with his victims could be the only key to unraveling his sinister motives, but will that be enough before he completes his ice-cold plot to claim his intended seven victims?