A Bay of Blood (1971)

Storyline:

Following the murder of Countess Federica Donati (Isa Miranda), an heiress possessing a beautiful piece of beachfront property, members of her family and the surrounding community engage in a killing spree, each with his own secret agenda. In addition to the string of creative murders, a group of hippies arrive on the premises, engage in promiscuous sex and find themselves dying one by one in this cult classic that's considered to be the original slasher film.