“If you tell someone a secret, it’s no longer a secret.” That chilling admission from a precocious child marks a haunting moment in Casting JonBenet, Netflix’s docu-drama revolving around the tragic unsolved murder case of the titular young girl from Colorado in 1996. This child is that girl’s brother. He was portrayed as highly suspect in her murder – despite being of a similar age to his six year old sister. He was later cleared of all charges, as DNA…