Were the 12 Angry Men Right?

In the 1957 classic “12 Angry Men” Henry Fonda finally persuades the other eleven jurors that, although the defendant may well have been guilty, the prosecution’s evidence did not establish beyond a reasonable doubt that he was the one who stabbed his father to death. In his systematic debunking of prosecution evidence, Fonda rebutted the inference that the knife found in the body must have been the unusual, decorated switchblade that the defendant purchased earlier that night after a fight with his father. Witnesses, friends of the defendant, identified the fatal knife as being exactly the same kind they saw in defendant’s hands on the street, and the shopkeeper testified that he had never seen another like it. In the most dramatic scene of the film, Fonda produced a second identical knife that he had bought down the street during the trial. Was that enough to demote the knife, together with the other evidence, below the reasonable doubt threshold?