The Psychopath (1966)

Inspector Holloway is in charge of investigating the murder of Reinhardt Klermer, Victor Ledoux , Frank Saville and Martin Rothand his main lead is a doll in each crime scene. He finds that the dolls belonged to the crippled doll collector Mrs. Von Sturm, who lives with her son Mark Von Sturm. Further he learns that the victims had investigated and incriminated her husband in the end of World War II. Inspector Holloway proceeds his investigation with a couple of suspects.