As to why, anybody that shoots a wounded/dead man who's no longer a threat is obviously a coldhearted, sadistic psycho..perfect description of Oswald?
Not really perfect at all. But you are free to speculate. Supposedly, the killer of the cop was trying to get away. So fugitives don't do that..they just get away.
Round and round over and over..Because he was a cold blooded killer Oswald did it...Oswald did it because he was a cold blooded killer.
When did he start this murderous life? There is still no absolute proof that Oswald ever shot anybody.