The most he could have gotten was manslaughter. The prosecution did a pretty lousy job.
You can't convict someone with a lack of evidence according to the way the law is interpreted. There was no proof that it wasn't in self defense. That's a problem with the law, not the jurors. Same thing with Casey Anthony, you couldn't prove who was responsible so you couldn't get a guilty verdict. That's the way the justice system is. People need to get their emotions out of the way and actually look at the facts of the case.