Too late now, but Z should never have been charged, especially after his justifed release after intense questioning by law enforcement, but reinstituted significantly later under social pressure.
Yes, he should have never been charged, but a significant minority of FL people believed T. Martin and always will.
More likely, Trayvon would have been charged with the murder of George Zimmerman—he was trying to grab Zimmerman’s gun to shoot him with it at the time he was shot.