Prayers go out for that father. Being a father and grandfather myself, I cannot even imagine what is now going through his mind.
I also wonder if we will ever understand what this fifteen-year-old thought he was doing or what he had intentions of doing. Masked and with a knife in his hand in his aunt's driveway at one o'clock in the morning? That doesn't sound like the nice, polite, easy-going kid description he was supposed to fit.
I also do not understand the police focus on whether or not the firearm was registered. Seems to me like they are fishing for something to charge this father with instead of trying to determine why the son acted as he did.