From what I've read the kid was caught trying to buy ammo online by teachers and he was drawing pictures and leaving notes implying he wanted to shoot up the school. They had multiple meetings with the parents over the matter and the parents did nothing, they actually bought a gun for their son.
it's illegal to give a gun to someone younger than 18. buying him that gun when he had clear signs of mental illness and warnings from the teachers might also reach the level of criminality.
If you can prove they committed ANY crime leading up the shooting, then you can make a case for involuntary manslaughter.
That's the problem with this case, the blurred line between negligence and crime. The school had meetings with the parents about mental illness, okay cool. Is following the school's suggestion mandatory in these cases? What happens if the parents don't have the money to get their kids mental health? What if their immediate area lacks the resources?
On the gun angle, was it a long gun or not? Because although federal law prohibits the possession of a handgun or handgun ammunition by any person under the age of 18. Federal law also provides NO minimum age for the possession of long guns or long gun ammunition. And some states can even sell weapons to 16 year olds, like Vermont.
In Minnesota, as long as it’s not in the city, you can sell a rifle to a 14-year-old without parental consent.
So, all in all, ascertaining that the parents willingly committed a crime is tricky in this case or at least it should be. Because you'd have to prove that they knew beyond a shadow of a doubt that their kid was conspiring to attack the school. How are you gonna prove that?
The school said so and so about the child, what if the parents felt like the school was being negligent with their kid?