She should but she won’t.
Internal Affairs will say that she “followed procedure” and the DA will decline to prosecute.
Yes, probably. But there is the recourse for the father to sue the officer and the police department in Civil Court for unlawful taking of the son’s life and to ask for treble punitive damages.
Essentially, with the right lawyer and jury, that police department and the town that supports it would be owned by the father.