I did not know that, but there has been a move in the last several years to blame the brother, but I think it is misdirection. Stun gun marks on her neck, intricate knots, etc. The son did some long-form interview as a now adult, and he certainly seemed creepy, but he was likely a victim as well and traumatized by everything. His wet sheets figured into the timeline, so were mentioned a lot, and bedwetting can be an indicator of abuse.

If the son was responsible, he was a very small child, so would have been acting out something he had seen or experienced and was likely an accident. I went down that rabbit hole a long time ago, very grisly and too confusing (with all of the family's behavior and connections) to come to any real opinion.