This much we can gather from the recorded phone call;
Neighborhood watchman sees a suspicious character.
Neighborhood watchman calls cops and tells them he is following suspicious character.
Cops tell neighborhood watchman to NOT follow suspicious character.
Neighborhood watchman follows suspicious character against police orders.
This much we suspect;
Neighborhood watchman approaches suspicious character against police orders.
Argument ensues and escalates.
This much we know;
Neighborhood watchman kills suspicious character.
My opinion? Neighborhood watchman is fucked. His job as a watchman was to keep an eye out and call the police if something aroused his suspicion. NOT to take matters into his own hands. I recognize and support that he has no duty to retreat. However, he had no authority to approach someone on the street for any reason. If it were on his property, yes. But if the kid was truly on the street or sidewalk, what the kid was doing was none of the watchman's business. For that matter, even if the kid chose to walk behind someone else's house, the watchman had no duty to follow him. He had already done his job as a neighborhood watchman by notifying the police.