The challenge here is that - according to Georgia's horrifically dumb stand your ground laws - they might very well be "not guilty" of murder... even though they clearly murdered him.

This is why a good and politically unbiased prosecutor is important in cases like these. It could be that while people "feel" a first-degree murder occurred, it may not be supported by the technicalities of the law and the available evidence in court beyond a reasonable doubt, and so it would result in a not guilty verdict. A lesser charge, such as voluntary manslaughter, might not be as politically convenient, but might be more likely to result in a guilty verdict.

Al Capone's a good example. Everybody knew he was guilty of all sorts of crimes--the judges, police, jury, everyone--but it took a tax crime to actually get a guilty verdict. If the prosecutor had only gone for the highest charge he thought justified instead of the charge most likely to result in a guilty verdict, Capone may never have gone to prison.