Here's a screenshot of the towel recovered from the area where Christine was located, and laid out and photographed at the crime lab.The testimony by LE that BB was not seen applying pressure seemed damning and CW asked about with towels, then about blankets then about sheets. All of those “no” answers plus his knowledge of her blood clotting disorder does not come off well imho.
The detective testified that there was no heavy staining or blood absorption on the towel, so that's further evidence that he was not using the towel to apply pressure, as the dispatcher was telling him to do.
