*If* the parents knew or should have known (and that's a big if), then they are accessories.
*but*, kids write and draw stuff all the time. That doesn't mean you expect it to happen. When I was in elementary school, we used to draw space battles and all sorts of stuff. I had a student teacher who had apparently just got done with that class and got it into her head that we thought that stuff was real, and we got very seriously questioned about it.
Well, duh, we know the difference between Battlestar Galactica and reality, but we're kids, and it's fun to pretend.
How many kids draw stuff like this but never have a problem ?
Maybe the schools should figure out why all of a sudden kids no longer have an outlet until they get to the point where they explode.
If you want to compare your spaceship drawings to his, by all means, do that. I will not.
Were these graphic illustrations of blood and guts of people around you? Did you also post on social media the evil things that you wanted to do to others? Were you on a rather large amount of anti psych meds?
Again, you may compare your childhood drawings to this 15 year old's drawing, I will not.