They have already released information that the police think it was an accident and she covered it up.
How can you charge someone with murder if LE thinks is was an accident and a lie that just got out of control?
What part of it was an accident???
She accidentally lost her daughter and then accidentally forgot to report it. She accidentally didn't have the job she said she did and accidentally didn't know the nanny she said she had or her address or phone #. She accidentally couldn't tell police where her daughter was or where she was for that matter. There is no accident here, she is a planner and a liar.
Another poster mentioned her saying in one of her jail conversations that the are going to pin this one her. I think this is very telling that Caylee is no longer alive. Because otherwise what would there be to pin on her. If she is simply missing at the hands of another this would be easy enough to figure out (if she were to tell the truth about it) and there would be no questions of Casey's innocence. They already pinned the child neglect on her because she neglected to report her daughter missing, so if that were her only crime in the matter she would not have any more to worry about getting pinned on her. I think she admitted right there that something serious happened to Caylee.
That being said I do believe 100% that it was intentional, maybe not planned out over a long period of time. I think it was maybe a rash decision and probably thought out and carried out within only a few hours. This is why she was not prepared to cover it up and only afterwards began trying to figure out how to cover her tracks, losing a phone, figuring out how to connect a nanny etc... There is no way you could go out and party and hang out with friends afterwards unless it were intentionally planned. She had worked out her grief before she had even done it and after she was finished she had rather accomplished a goal than done something horrible. Now she was able to go forward with her life as foreseen by her.
Had it been an accident she definately would have reported it, even if it were in some way her fault. Don't you think with all of the lies she has told that she could not have thought up some way to explain an accident that would bring some attention and sympathy to her "a grieving mother". She is too self preserving to not tell who the kidnappers are or to not admit to an accident if she thought it would help her. The problem is that if she were to say it were an accident then she would have to lead them to a body and they would likely be able to prove otherwise.
I also think that even if there were other parties involved she would not hesitate a second to expose them in order to get herself off or a plea bargain or something, I could even see her pinning it on them. Even if it could possibly cause harm to Caylee to point to the alleged kidnappers she would still tell because she cares far more about herself. If she could get herself out of jail and harm actually came to Caylee at least it would not be her fault.
The problem is she did not plan this out beforehand in order to cover her butt, there is not an accomplice, there is not a kidnapper, and it was not an accident. She has no outs and knows it, therefore she is waiting and hoping for some way to get out of her intentional crime.