My defense theory on why Casey did not report Caylee missing is that she had a lot to lose by calling 911, so she "tried to handle it" on her own - as she said "which was stupid" as she said. Further, in my defense theory, Casey thinks that one of her friends took Caylee to teach her a lesson, so, she doesn't realize that a SO took her. She thinks it is one of her friends who has access to the Anthony house. But the truth of the situation is a SO broke into the house and took Caylee. So while Casey is busy covering up that she doesn't know where Caylee is to everyone (both her parents and friends) while trying to figure out which friend has Caylee and where he/she has her, unbeknowst to her, Caylee is killed or has been killed by the SO.
If the SO is this person:
http://www.wftv.com/news/19489838/detail.html
Well, what the heck was he doing with the 4 year old child in the garage? Was his plan to molest her and then kill her? Was he going to triple bag her with the toys, shorts and blanket and put her in the trunk of her parent's car? We have no way of knowing what his intentions were because, thank God, the child was able to get the duct tape loose enough to scream alerting her parents to the intruder. The report also mentions beer cans at the scene. There were beer cans where Caylee was found, along with a bunch of other junk, but that doesn't discount that there were beer cans there. And the perp has apparently been doing this since at least 2007. He tried kidnap an 8 year old in 2007 - but these are ONLY the ones we know about! AND if you read the report about the 8 year old, it appears the man tried to enter the home on more than one occaission.
So why did Casey lie to police?
I think because her friends were the MOST important thing to her, she didn't want to lose them, especially not the new boyfriend, so she made up the lie about the nanny hoping to pacify Cindy until she could go to her friends and ask for help - I think she didn't want to get her friends in trouble. Then Casey was stuck telling the lie to police because her mom was sitting right there. She really had no story, nothing to tell them. I think she didn't anticipate being questioned and arrested and figured she'd get away from police and beg her friends to return Caylee. But, of course, that wouldn't work if her friends never had Caylee to begin with.
Why didn't Casey tell the police the truth when they confronted her with her lies?
Because she thought the person who had Caylee was someone she has feelings for and didn't want to get them in trouble.
Why not talk to police afterwards and straighten the situation out?
Because her attorney advised her not to.
Again, I think Casey is probably guilty (like 99% - I'm giving her a 1% chance she could perhaps be innocent until the trial is over). But if I set aside personal prejudices, I do see how a SODDI case could be made and this is my attempt predict what the defense case may be.