I know the shooter isn't out of the woods yet. If there is enough outcry I think the prosecutors could file charges later. And even if that doesn't happen he will likely get sued and that will be even harder to defend against. I suspect that if he had any money it will soon be gone.
If the DA refuses to prosecute due to his burden of disproving self defense under the stand your ground laws, the defendant would then have immunity under that law.
“Immunity” refers to a complete protection from being sued in the first place. In the context of a criminal assault case, this typically means the police can investigate the assault, but cannot arrest the defendant unless there is probable cause the use of force was not permitted under the stand-your-ground law.
In a civil assault case, if a judge finds that the defendant is immune under the state’s stand-your-ground law,
the plaintiff will be forced to pay the defendant all of the expenses the defendant incurred defending the law suit (e.g. attorney fees, court costs, lost income).
As long as he doesn't have to prove an affirmative defense -- that self defense was justified -- he has immunity.
If the DA decides to take him to court, he loses immunity if SYG isn't affirmed in a pre-trial hearing. Immunity is the key to whether or not he can be sued by the dead guy's estate.