The cult featured in the film, the Black Circle, was based on an actual group. In 1984, in Northport, Long Island, a few High School dropouts formed a cult named the Knights of the Black Circle. Two of its members, who were both heavily involved in drugs, brutally murdered one of their friends when he refused to profess allegiance to Satan. Their story became the basis of the book, "Say You Love Satan". Incidentally, the exteriors of the Besler house were shot in Northport, only one block away from the crime scene itself.
"Night of the Black Circle - a true story of ritualistic killing" about Ricky Kasso was added as a supplemental documentary to the main feature.