There's one thing about razors - one side can be sharper than the other. That's how you get those little cuts you don't expect when you're shaving....
While you're talking hard evidence, the cell phone records are evidence also. Psychological behavior can play a part in this too, and specifically the legal term "consciousness of guilt." As we have heard all the 911 calls, the first jail call, and subsequent Lee/Casey calls, Casey doesn't appear to care about the search for Caylee - only the pursuit of protection and defense for herself. In this, she lends the perception of behavior attributed to Scott Peterson, Ewing Scott, Richard Crafts and a whole host of other missing person's cases: they did very little, if anything at all, to find their missing loved ones. Mostly they lied to continue the mis-direction for the investigators, always pointing away from themselves. Why? Because they already knew where their missing loved ones were. Casey, in her phone calls with her parents, the 911 calls, the calls with Lee all have the general theme: it's about her, not finding Caylee. She appears she doesnt want Caylee to be found, the "Caylee's life could be in danger" and "I'm protecting her" statements. Really, one could almost look at that statement as form of displacement because it could read:
"My life could be in danger and I'm protecting me"