Maniac (1980)

Frank Zito misses his mother, who was killed in a car accident years before. She was abusive to him, and made money selling her body, but Frank still misses her. He tries to keep her from leaving him, and reform her evil ways, by killing young women and putting their scalps on mannequins which he displays around his apartment. Photographer Anna D'Antoni takes a picture of him in the park, and he pursues and befriends her. Is she the one he has been looking for or just another mother wannabe?