My very first thought when I first head about this was that Cindy and Casey were in it together, and were trying to cover for each other. When Casey called home and said "you don't know what my involvement is?" with so much amazement in her voice, it just seemed to me that she was kind of saying "Mom, you know all about this, and you're denying that you do". I still think that Cindy is involved in it up to her eyeballs! JMO
I think that is the only true statement Casey ever made during this entire ordeal. Everything else is a lie.