I actually think it’s wrong to charge parents with crimes if their children kill themselves accidentally. I think losing their own child is punishment enough.
In cases where someone else dies, I would think it would be up to the prosecuting attorney to prove that the owners of the dangerous thing were unreasonably and exceptionally negligent to a degree that would make them responsible.
I didn’t read the specific case, but it seems to me that as written, the question in the title:
“If a child shoots himself or someone else because he got his hands on a gun, should the adults be charged with a crime?”
– Should be answered “not necessarily, it depends on the circumstances”. The question is worded such that a child getting his hands on a gun equals responsibility for a child killing him/herself. It seems to me there would be other aspects of the situation needed to amount to liability for the shooting.
For an example of an actual case I do know about, one man took three children hunting with rifles. No one thought the rifles were loaded, and one went off while held by one child, and another child was shot in the leg, and had to be taken to a hospital. That’s an awful thing, and even though I didn’t see it happen myself, hearing that story as a child made me not want to deal with real guns. But I think it was an accident, of a type that can happen with guns, and by itself as described does not amount to criminal liability for the adult (unless perhaps he didn’t have the child’s parents’ permission to do that, but I am sure he did).
Not all dangerous or even potentially deadly things mean that someone has to be guilty, or that something has to be outlawed.