We don't just have Robyn's word that Casey responsed differently to televised reports that bones were found in the river than she did when she heard bones were found on Suburban. Released discovery of prison employee interviews report that Casey became flushed, doubled over and asked for a sedative when she heard about the body on Suburban. When bones were found in the river by divers she didn't even stay in the room to watch the television. IIRC, a jail employee leaked to the media that Casey said, it's not her, when it was being reported that the diver found fingers.