We know the story. Only the names and superficial details have changed. Lillybing. James Whakaruru. There are too many. These are names that should shame us. Shame us into action. Shame us into weeping. And now we have the Kahui twins.Do you see it? Can you spot it: What's with the 'we' white man? Why should I be shamed? I didn't do it. I didn't kill them. Did you? Did Marc? Of course not. Any action provoked by such a poorly conceived starting point is going to do less good than its promoters might like, and will probably only do more harm.
Who is responsible is not you or me. It's the person or person who did kill them. That's who's responsible. Not society; not 'we'; not 'us': just the murderer(s). These aren't 'our' kids; they were the Kahuis, and that's who's responsible -- no one else. Just them, or the people that the law finds responsible.