And there is a reason why cops became murderers. So instead finding the cause and fixing it, you say that they should go to jail and end of story?
The problem is, that this is how our current prosecution system works and it fails on so many levels. So why do you think it would work on them? It doesn't make the world a better place and there aren't less criminals because of it. Then why do you think there will be less trigger happy cops on the force?
People still commit crimes even with the risk of getting in to jail. Cops will still shoot people, because they will rather go to jail then be dead. Even if there is no gun, it is much safer for them shooting first and asking later.