Whispers (1990)

In this adaptation of a novel by famous horror author Dean R. Koontz, the story follows Hilary, a journalist who becomes the target of a relentless, incredibly enraged and extremely violent psychopath bent on murdering her at any cost. After several nearly successful attempts on her life, she manages to recognize her attacker as Bruno, a man whom she once interviewed, but fails to understand why he would want her dead. Later, she manages to kill him in self-defense, but then he shows up again, this time seemingly sane and without any knowledge of any of the attacks. The police do not believe her story, but a detective named Tony sympathizes with desperate Hilary and agrees to help her investigate the matters further. They soon realize that Hilary is not losing her mind and that someone - or something - really is trying to kill her and that Bruno's past may very well be the key to solving this terrifying supernatural mystery.