Everyone is assuming that Caylee was killed on the night of the 15th, or the 16th (Depending on whether you believe George saw them or not). If Casey was handed a dead Caylee.......say on the 17th, and it was by her lover AL.....and he told her that she was killed because of some sort of illegal activity that AL was involved in, Casey could in no way explain this to her parents, nor inform authorities, per AL instructions. This would explain why she wanted to talk to AL soooooooo Bad when she was first arrested. She may not know who specifically killed Caylee, because AL may not be willing to tell her, because it will put her and her family in danger. This is yet another scenario that the defense could use, putting AL under the bus for abuse of a corpse or whatever else they can dream up. This is a far fetched scenario that is not at all what I think happened, but, in someone's wildest imaginations it could be possible.