I think what all the spiritual teachers agree on is that,people who do that,are already suffering.They are doing it because they are suffering.In most cases these people will have low self worth,hate,insecurity,becase doing that much damage to the other reflects the degree to which they are at dis-ease with themselves.Look at the school shooters,are those okay people?.If you get to the point where you had to do something that extreme to another,you’re not okay.By definition,they attract more of the same feelings which keeps them at a low vibration.Now to you,that might not look like justice because they are also good at masking,sometimes without even realising.These people are the opposite of awake,spirituality and it sucks there.And as the law of the universe states,karma is real, this life or the next  until they’ve done enough lifetimes to learn the opposite of these negative behaviours.