He won't "go free" as long as Holder is at the Justice Department. If found "not guilty" in the state court, he will be charged with a federal crime.
That is not considered double jeopardy and there are plenty of precedents.
We’ll see. My predictions. Nothing will happen with this case before the election. Within 24- 30 months Zimmerman will be cleared. He will sue NBC, CNN and other for millions. Eric Holder will be gone by November. Obama will lose. The Feds won’t get involved. There will be riots but they won’t be in white areas so few non-blacks will be affected or ultimately care.