Sigh. I'm hearing that Florida prosecutors did not prove their case against George Zimmerman beyond a reasonable doubt. For example, BBC News reports that "Alan Dershowitz told BBC News that there was "reasonable doubt" about the facts of what happened." Dershowitz should know better: reasonable doubt is not an issue in the case, and if it were, Zimmerman would have been convicted.
The part of the case which the state's burden to overcome reasonable doubt would apply is as to whether Zimmerman actually shot and killed Trayvon Martin. However, this part of the case is not in doubt; Zimmerman admits to killing Martin. That's all there is for the prosecution's reasonable doubt.
Zimmerman did not try to raise reasonable doubt; instead, he raised the affirmative defense of self-defense. (Florida's "Stand Your Ground" law, which establishes that a person can claim self-defense even if he or she refuses to retreat, does not apply, because Zimmerman claimed that Martin had restrained him and he was unable to retreat.) An affirmative defense requires the defense, not the prosecution, to bear the burden of proof. The defense's burden is typically lower than the prosecution; the defense has to establish an affirmative defense not beyond a reasonable doubt but by only by the preponderance of evidence. The defense successfully argued that Martin attacked Zimmerman, and Zimmerman shot Martin in self defense.
It is possible that Martin really did attack Zimmerman. However, whether or not he did so is completely irrelevant. The relevant facts, which are not in dispute, are that George Zimmerman armed himself with a pistol, and went out of his way to intentionally create a situation, stalking and harassing Martin, with a strong likelihood of a violent confrontation. George Zimmerman could have prevented Trayvon Martin's death: he knew that his actions could cause Martin's death, he knew that by not intentionally provoking him he could have prevented Martin's death, he knew that he had no good reason to intentionally and deliberately create a situation that might lead to Martin's death, and he did so anyway. That, in my mind, makes Zimmerman an evil bastard guilty of the murder of a child, and our society complicit in that evil by exonerating him.