Rent Amityville 3: The Demon (1983)

John Baxter, an investigator of psychic frauds for Reveal magazine, unmasks a fake medium racket operating in the Amityville house. Baxter then discovers the property is going cheap due to the house's reputation and buys it, sceptical of its history. But once moved in he is hard pressed to find explanations for a series of supernatural events. Before long the evil in the basement awakens to claim more innocent victims...