Zimmerman’s practical choices might well be to plead to Manslaughter or federal trial and conviction of civil rights charges. The DOJ is watching and ready to “rectify” any error on the part of a state court. Trial and acquittal in Florida will get Z arrested and tried by the Feds who will get whatever Decision they want.
Zimmerman wasn't acting "under color of law" (ie. as a state agent) nor was there any alleged conspiracy involved. It wouldn't be as easy to try him in Federal Court as it was for the Rodney King cops or the old South Klan affiliated cops. I don't care about the legal fictions recognized by the law to justify it, to make a man stand a second criminal trial in a case like this is the epitome of double jeopardy.