I think there were probably at least some internal contradictions. Thats what makes this case so bizarre. The evidence seems to point everywhere and nowhere.
That's been the real problem all along. How could it be the parents? Who would do that to their beautiful little girl? But how could it be a stranger that is at once stupid enough to murder a child not once but twice and pen a useless long rambling ransom note yet clever enough to drift in and out of a huge home without drawing attention or leaving a great deal of trace evidence? It boggles the mind.