Sounds like defense may try to go with an "accident" theory. But I don't think it would attempt such a defense without Casey testifying that it was an accident. Jurors aren't going to be sympathetic to some lawyer showing jurors how it "could" have been an accident when Casey has NEVER said it's an accident and is sitting right there in the courtroom watching the "accident reenactment" without saying whether it's accurate. Even though Casey doesn't HAVE to testify at trial, for the "accident" theory to work I think her testimony would be needed.
In that regard, I think it would be easier than one thinks. Casey testifies that an accident happened (drowning, whatever) and that she became distraught and scared, calling her parents at every number for over an hour straight. She throws in a sob story about how she held her dead baby crying for the rest of the afternoon. After that, she's in shock and denial and comes up with the "kidnapping" story b/c she's ashamed of what happened and feels guilty about the accident and doesn't want anyone to know Caylee is dead, for fear of breaking everyone's heart (and for getting in trouble herself). Instead, she goes on acting like she is still alive for the sake of those who love Caylee and also b/c she is in denial herself about it. When she disposed of Caylee's body, her mouth was leaking nasty fluids and there were flies in it and it broke her heart to see it. Or maybe Caylee's lip was torn off at this point - who knows. So she covered her daughter's mouth with duct tape and put a heart on it. She buried her close to home b/c she wanted 2 be able 2 visit her easily. As for the rest - she lied to everyone about everything (Zanny; etc.) simply b/c she didn't want anyone to know Caylee was dead because (1) she didn't want to get in trouble and thought it was "too late" to report it; and (2) she didn't want the Anthonys to know their poor grandbaby was dead. Arguably, none of the "evidence" (decomp in the car, same laundry bag at the burial site) contradicts this story. Casey - "Yes, she was with me when she died (accident) and yes, I buried her and yes I lied to everyone b/c I didn't want anyone to know. And there was nothing I could do to bring her back so I went back to living my life and tried not to think about it. Part of me was in denial."
I'm concerned that a jury could "buy" the above. That's why I'm interested to know when Casey wrote the journal entry saying "I'm happy with the decision I made. I hope the end justifies the means." If she wrote that a few days after Caylee's death, I think it goes against an accident theory. Maybe doesn't disprove it, but really calls it into question. Presumably, she wasn't talking about some innocuous decision, like changing the color of her hair highlights. Also, I hope they are able to tell whether the duct tape was placed on Caylee before or after her death. If prosecutors can show duct tape was placed on Caylee's mouth while she was still alive (Dear Lord Help Us All), then the accident theory goes out the window.