Except, in Florida (and most everywhere else in this country) killing someone in and of itself isn't a crime. Someone, 3rd?, posted the conditions that have to be met in Florida for 2nd Degree Murder (and the lesser charges). The DA had to prove all the conditions were met to bring the killing to the level of a criminal offense. 6 jurors determined the state did not prove it's case.
It is still innocent until proven guilty in this country. And the jurors determined that because he was acting in self defense, that GZ wasn't guilty of the crimes he was accused of having committed.