Imho, the problem w/the abuse scenario is that it "assumes" this child did, in fact, shoot his father and his father's friend. But... just "what if" someone else shot them and he witnessed that shooting? How easy would it be for him to not only be afraid to talk but to also believe that he was in some way, responsible for his dad's death?
It's called magical thinking and kids engage in that a lot... thinking they're responsible for a loved one's death when said loved one is dying from a terminal illness... thinking they're responsible for mommy or daddy leaving when mommy & daddy made an adult decision to divorce based upon adult reasons that they cannot possibly understand... thinking they are responsible for their dad's death for not protecting him from an intruder...
In the end, we may find out that he did in fact shoot his father & the friend. Otoh, I personally, have a problem when LE announces within hours of a horrific crime, that they have the perp based upon said perp's confession. Esp when said perp is an 8 year old child.
If this child is innocent, then his victimization has been compounded by a shoddy investigation. One that has painted his father as a possible abuser and him as a cold-blooded killer. If, otoh, he is guilty as charged, then, imho, we, as a society, might want to sit back and consider what it is about our current climate that is breeding killers at younger and younger ages.