Okay, my bad. They are still humans, but they are no longer Mortal, and thus do not fall under the preview of the Laws of Magic.
Even that isn't necessarily true. I suspect the Council would say that in general, yeah, it applies, and I'm pretty sure the universe thinks it's killing a human with magic. I think the universe would consider it to apply with White Vampires, too.
But there are a grey areas in play at Chichen Itza. For ex, Harry killed a Red Vampire, with a knife. No violation. The death of that Red Vampire, in that specific place and at that specific time, triggered a magical effect, but Harry didn't set any of it up, didn't charge it, none of his personal magical energy was involved.
So was Harry casting the magic, or did the Red Vampires cast the magic using somebody doing the sacrifice as a component? First Law status unclear in terms of Council legality, unclear in terms of cosmic law.
If Harry was casting the magic in the eyes of the Council and/or the Cosmos, then was it a case of self-defense? Or at least defense of others? A good argument can be so made. The Council acknowledges self-defense exceptions, and the Cosmos seems to consider it am extenuating circumstance, killing with magic in self defense seems to leave less 'taint', less damage, on the person doing it.
Self-defense status: Unclear in both Council and Cosmic terms.
The magic ripped away and destroyed parasites from the humans who were being preserved and sustained by said parasites. Most of those humans then died of old age when the preserving effect was removed. But was this a case of death from magic, or from natural causes long delayed? Council Law status unclear, Cosmic law status unclear.
It's just not clear who was guilty of what or innocent of what in that Charlie Foxtrot.