Seven Blood-Stained Orchids (1972)

Sinopsis

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?