In the end, someone must be caught and identified as the murderer, and either arrested or punished. The resolution of a mystery should not be rushed by so quickly that no one is quite sure just who really did it, but the alibis and confessions of the characters should be clear and to the point so that there is no question in the audience's mind as to what everything meant.

We have found it helpful, and more dramatic, to go down the line of suspects, accusing each and acquitting each in turn, ending with the murderer, who is then accused, confronted with the evidence (i.e.: the clues are reiterated), and who then confesses to the crime, just so there is no doubt as to their guilt. Then, and only then, are they dispatched with.

Be certain that the punishment fits the crime -- a criminal getting off with a slap on the wrist is closer to reality, but in the universe of a mystery justice must prevail if the audience is to be satisfied. The scales must be balanced.