The only question I’m really concerned with is how much/little did his parents know - I really don’t care how he died (unless his parents did it — like some Of Mice and Men sorta deal)
You will have to ask their lawyer, doubt that information will ever be really known.
It's sorta like how Lee Harvey Oswald was killed by Jack Ruby, a lot of questions to be answered, but no one really seemed to be questioning police how that happened....How do you have someone in custody in a police station and he is shot dead? Anyways....
Maybe the specialist can figure out how Brian died.