One or two coincidences does not prove murder. The coincidences and circumstantial evidence presented by the prosecution, however, paint a pretty clear picture of what happened. Cloroform in car, cloroform search on her PC, dead body smell from K9 search, post mordem hair in the trunk, Casey admitted abandoning the car, not reporting a missing child for a month, partying after her kid went missing, lies to the police to cover her tracks. Obviously, analyzed seperately, the evidence is circumstantial and not sound, but if you view it all as part of the big picture, the evidence is enough to prove guilt. To me, the string of evidence removes all doubt of not guilty.