I am not saying that Casey was insane or anything but what I have been thinking is maybe something happened to Caylee, either accidently or delibertly and Casey just had a break of reality. I know that when I was younger I had something traumatic happen to me and I just shut down and didn't remember what happened for years. Maybe in her fragile mind this was the only way of coping, just blotting it out and not accepting it. She had told the story of the nanny so many times that she convinced herself that the baby was with the nanny and truly believes it to this day. We all know Casey is mentally ill, just how ill is she? I'm not saying she should be not guilty just because she had a break with reality but maybe she really doesn't remember?