In which I decide to start trolling people who use karma to mean “what goes around comes around.” This is the equivalent of a buddhist saying to a christian: “sin is when you feel real bad but do it anyway.”
Karma was explained to me by one Zen priest as simply a reaction from your environment. Plain and simple. What you do causes a reaction, but this reaction is not correctly understood as whatgoesaroundcomesaround. That’s like saying: well, if I kill someone then I will be killed later. That’s a vast oversimplification. Killing someone would most likely cause suffering on both sides, killer and victim, unless one or both of them were sociopaths or otherwise mentally deficient. The families of both would suffer. The community would suffer. The criminal justice system, and all the karma-bound beings in it, would have to do its bit and would bring all their past mistakes, prejudices, hopes, etc. to bear.
Maybe the killer in this instance got lucky. Maybe they were old rivals. Simply put: the world is not that just, all on its own. It is a mistake, at least from the Zen perspective, to try to humanize karma as though it something we easily understand and control. It simply means law, as in: law of the universe. It is what we strive to understand through buddhism, not what we control or manipulate for our own benefit or to score points off of someone else. That kind of “gaming the karmic system” mentality only adds more suffering to the equation.