If the scenario is true that some have posted on here, ie;she drowned,casey paniced, went to sawgrass apartments and pretended to be Zenaida to make it seem like there was really a Zenaida, then one must think like Casey would possibly think in this state of mind.
She was working on the premise that Zenaida had Caylee and did something to her or was neglegant and let her wander off and drown in lake or pool at complex.
So where would she put the body? Next to Sawgrass apartments. It makes sense. This is the only place that she tried to tie in Zenaida having Caylee at. So she concocted a story that Zenaida was watching Caylee, never returned her, went to the apartment with the police as a witness that apartment was vacant as if Zenaida left town suddenly. Figured they would search perimiter of apartment complex, find body, and look for this Zenaida as perp.
Meanwhile she did not think that, police would contact Sawgrass management, find out Zenaida never lived there, do dna on car (she probably thought it would get stolen), she would get arrested, and they would find out she was out partying it up instead of her story that she was out looking for Caylee.
If I where LE I would look in vicenity of Sawgrass apartments. If you think like a 23 yo party girl who panics and is really bad at covering up things I think you will see that this makes sense.