Really? A person ceases to be a threat just because they're no longer standing?Murder.
If the kid was down on the floor he is no longer a threat to the store clerk...
Is self defence not a valid defence in the US? I think it's a fundamental right of an accused person to enter any defence that they honestly believe valid. If, based on the evidence here, you are annoyed by any plea, I sincerely hope you never serve on a jury!...It annoys me to see people like this man trying to hide behind self defense...
He may have been able to suppress some threats as you describe, but not knowing what threat he believed he faced, it may be argued that his actions were justified....he could have handcuffed him or tied his hands and legs. Then call the cops.
As for any reliance on the cops, well I'm not sure I would always trust the police, and certainly not enough to put my life, or that of my loved ones, directly in their hands.
I disagree with your certainty; by walking back into the store, he may have been concerned with the safety of the other staff members, and actions could therefore be validated as 'self defence' IMO....The owner was outside and safe... ...by walking back in to that store he had only one reason to and that was to finish off that person...
Cops will tell you a lot of things, I've learnt not to believe a lot of it, and think for myself... I'm better at it than most police I've ever met....Cops will even tell you if you can get out do not go back in to a dangerous situation.