Casey Anthony trail question./duct tape question?

Well I suppose it could have been placed to keep the jawbone in place and then the person who moved it decided to just put it in the trash bag instead to move it. Or maybe they thought the trash bag would cause her to decompose faster? There is really no way to know what happened to that girl, other than the fact she was found dead six months after being reported missing and that her mother partied the entire time she was "missing" and long before that.