No. The farmer who was arrested for shooting someone had chased the intruder outside, then shot him. Is that legal in the US, once an intruder has left? Can you chase him down and shoot him>
No, you may not chase down and shoot anyone in any state in the US. that is not considered self defense.
You have to be credibly concerned for your life or the lives of innocent others to shoot someone; if someone is running away he is clearly not a present threat.
“No. The farmer who was arrested for shooting someone had chased the intruder outside, then shot him. Is that legal in the US, once an intruder has left? Can you chase him down and shoot him>”
Depends on circumstances and state law but generally no you can’t. Once the physical threat to yourself and/or others is over best not (unfortunately).
How does one know hes not retreating in order to regroup, or get other mates to come back again in bigger numbers?
Your example is a farmer guy who is an old man who suffers a suprise attack by a criminal. Those are two things that in America justify his reaction, look up Disparity of Force.