The case had been built-up by the 2 previous episodes of the crossover (not the best one, but still). We knew this was the guy, we cared for the victims, it was just their job to tell us why he did it and make us LOVE the way they proved it. Well, the motive was weak, weakly explained, weakly delivered. Even for us knowing he was guilty, it didn't make sense, so it would be very hard to be believed by the jury. The worst part is that the actual motive which technically is what Stone's team are looking for the entire episode, is never mentioned in trial and when they finally tell the jury in closing arguments, it is delivered poorly. Boring episode.