Proof beyond a reasonable doubt. Saying she must have killed her kid because we can’t think of anyone else that might have done it is not proof. Saying someone “acted guilty” is not proof.
You would be amazed at the emotional instability that sets in on a person once they feel the eyes are watching. People no longer act like you might expect. Even you would act guilty of a crime you knew someone else committed in another State you never even knew if you thought someone was watching you for signs of guilt.
No, I would not act guilty if I had not committed a crime just because someone was watching. If I had accidentally and unintentionally killed my child I’d call 911. If my child disappeared I’d call 911. Casey’s child was missing and she didn’t call 911. Instead she went out and partied. That’s because she knew where her child was and she knew she was responsible. She didn’t want anyone else to know. Once the child was disposed of her only problem was keeping her nosy parents out of the picture. Obviously she wasn’t thinking long term, but she was free to have a good time while it lasted.