Think Progress has the story:

In early July, 20-year-old Colt Thriemer shot dead a one-time friend in a Wal-Mart parking lot, saying he feared for his life. Witnesses gathered for a truck meet that night say victim Thomas James Brown, 21, was walking away toward his car when Thriemer fired ten shots. Some say Brown had threatened to kill Thriemer over the course of several weeks. The story as told by prosecutors in a detailed legal memo suggests drug transactions, addiction, and monetary debts all played a role in the scenario leading up to Brown’s death.
But these facts will never play out in a trial, because prosecutors have decided not to charge Thriemer citing Florida’s Stand Your Ground law.
“The Stand Your Ground statute makes no exception from the immunity because Brown may have been walking away from Thriemer at the time the deadly force was used,” the memo from the State Attorney’s office states. “The Stand Your Ground law does not require Thriemer to wait until Brown in fact retrieved a gun before he fired. Under the current state of the law and the facts of this case, Thriemer was legally allowed to use deadly force based on a reasonable belief that his life was in danger and that he was about to become the victim of an armed robbery.”
If all of this information is correct, if an unarmed man was shot by an armed man standing his ground, then the incident can be seen as a moment, a scene, a normal happening in the kind of society the NRA has in mind for America's future.