The one and only time I served on a criminal jury I was frustrated by the way some of my fellow jurors wanted to play amateur detective and "solve" the crime themselves. I had to keep reminding them that we could only deal with the evidence and arguments that had been presented to us, not invent our own theories and explanations . . . .
"Hey, maybe it was case of mistaken identity and the cops nabbed the wrong guy, who just happened to look like the real perp?"
"Um, that's a fascinating theory, but given that neither the defendant or his attorney offered that defense, I don't think we can consider it . . . ."