I feel there must be a way to have the consequences occur somewhat naturally. That's DayZ's biggest game play design challenge.
Giving human-killers a mask seems too artificial but how else to do it? It would be more natural if having 2 sets of eyes (and trigger fingers) outweighed the benefit of killing someone so that's a more organic way to handle it but it's a hell of a balancing act, and probably one that varies depending on how many players there are.
One thing that could help is for some loot to be destroyed when a player dies. Not all of it, but if you fire a pistol at someone holding a rifle and one of your bullet happens to hit that rifle, it's reasonable for that rifle to be at best damaged when you pick it from their corpse. Again, this is a tough balancing act because other humans should be dangerous and you should be worried about them stabbing you in the back, metaphorically or literally.