it takes a huge stretch of the imagination to find ways he is not involved....
If they were involved, they would have just dropped him off somewhere and not told anyone anything, and brought the vehicle back home? At any rate, they can’t be compelled to testify against a family member, so there would have to be solid evidence of aiding him. I am very reluctant to start blaming his family members for anything he might have done, until he is found and more facts come out. And there is no telling what Brian told his parents, either. Not that he might lie to them or anything...