Michigan has no law for a mandatory lock box for guns but the prosecutor has brought charges of unintentional manslaughter against the parents who have since diaappeared. The son is charged with first degree murder. The manslaughter charges require proving 3 things of which trying to prove intent is always an uphill challenge.
Charging kids as adults has been around for decades as part of a get tough on crime program.

The FBI is mad at the prosecuter for not charging parents while in custody and the prosecutor is mad at the school and the families are sad beyond belief. The gun manufacturers and customers feel happy as a ... fill in the blank.