neighbor kills neighbor over dispute and has no regrets

A man was clearing some bushes from a strip of land between his house and his neighbors.  His neighbor came over to talk/confront him about clearing the bushes and the first neighbor killed him.  he was shot twice, once in the abdomen and once in the head.  The shooter was convicted of   first degree murder.
     I've had good neighbors and I've had bad neighbor's.  One neighbor gifted wrapped doggy poo and left the gifts scattered on my front lawn.  I had another neighbor let his boxers roam the neighborhood and the dogs loved my yard.  One was constantly jumping in my koi pond trying to catch my fish.  I now have a new neighbor  who appears to be running an illegal daycare and the traffic is horrendous.  They have already gotten into a dispute with a neighbor adjacent to them about the property line. 
    I have neighbors I dislike their ways because they are noisy or nasty people (at least their yards are).  I prefer natural fences like trees  and bushes and grape vines because they are cheaper to put up and return many benefits to me while privacy fences and chain link fences only cost money.  Of course fences are good for keeping pets in the yard and I've owned houses that had fences.  sometimes they are necessary but I'd rather do the natural thing.
   I've been able to solve most of my problems with my neighbors by having a friendly conversation with them, working hard to make my yard functional and beautiful, by being a good neighbor myself, finding solutions that are mutually beneficial to everyone concerned and getting the police involved only as a last resort or when it is the wisest course of action.