Une Journée bien remplie (1973)

Synopsis
This black comedy is the first film directed by the French actor Jean-Louis Trintignant. The story concerns a baker (Jacques Dufilho) who has carefully planned the execution of the nine jurors who sent his son to the gallows for murder. Before the police or anyone else can stop him, he calmly does away with each of the nine in a grim but methodical way. During his own trial for the murders, our attention is called to his parents as they carefully photograph those jurors. ~ Clarke Fountain, All Movie Guide