You didn't see the report that he asked LE (when he was arrested) "Did you arrest anyone else?"
That is, so far, his only public utterance. Why would he ask that? I figure he might have been afraid that his parents would be arrested, is my null hypothesis right now. And maybe they did. And maybe they will be charged. We don't know. But BK is the one who put the idea in everybody's heads.
The other people involved do NOT have to have helped commit the murder. Maybe someone drove the Elantra that night. Maybe his parents knew he was the killer and harbored him. We do not know.
I am definitely speculating, but I think his question was intriguing (my guess is still that he worries that he has compromised his parents or other family members). Weird thing to ask, don't you think?