I think the official reports might not be in hand yet, but that they're probably getting updates from the lab and already know most, if not all, the test results.
I envision LE doing all sorts of things behind the scenes. Tracking down places Casey made purchases with her mom's card, trying to get surveillance tapes for those dates from those places; triangulating (if that's the right word) the cell phone calls to see where she was and when; combing the computer for clues, etc. I think there's a lot more forensic evidence than we've been privy to as well.
I have no doubt they're working it and working it hard and will put all the pieces together. Even if Caylee can't be found and even if Casey never speaks, there will be enough solid circumstantial evidence to build a strong case against her.
The truth is gonna come out one way or the other, whether Miss Casey Anthony likes it or not. She'd serve herself well to cooperate and beg for mercy before they've done all the work and no longer need her cooperation.