@Mame,
Who knows what might have worked for the defense?
As I said, I thought the focus of the closing argument was risky, It is possible that an "it wasn['t murder" argument might have worked (although given the speed that they reached the verdict, maybe nothing would have worked).
It is difficult to guess what the jury deliberation was like. Did they all walk into the room thinking "guilty" or did some of them have to be convinced? I know a few people who were thinking "manslaughter not murder", to get 12 people to all agree to a murder verdict so quickly is interesting.