Getting Away with Murder (1996)

When the very moralistic college ethics instructor (Aykroyd) finds himself living next door to an accused German death camp commander (Lemmon), he takes it upon himself to rid the world of this man. And even though he manages to kill him, he does it so cleanly that no one accuses him and it isn't until he guiltily marries the German's daughter (Tomlin) that he discovers the truth about the man...