“In a hearing last week, a juvenile court officer said Brown had no serious felony convictions that would be public.”
meaning ... He has serious felony convictions that would be kept from the public.
Well, no. The state law that permits sealing any records of a juvenile when he turns eighteen have an exception that permits releasing records of convictions of serious felonies. The court was saying it doesn’t have anything that meets that exception. They didn’t comment one way or the other regarding the possibility of any other records.
That’s the way I read it.