Night Visitor (1989)

High-school student Billy (Derek Rydall) is a born liar who annoys his teacher, Mr. Willard (Allen Garfield). When gorgeous prostitute Lisa Grace (Shannon Tweed) moves in next door to him, Billy is fascinated by her -- and shocked when he sees Mr. Willard murder her. He goes to the police, but they won't believe him. Worse, Mr. Willard, who is a satanist, knows what Billy saw. With no one else to turn to, Billy seeks help from his late father's old police partner, Ron Devereaux (Elliott Gould).