Sometimes people confess to their lawyers. They know the lawyers can't tell. She may have done so because she felt internal pressure or because JB was pressuring her. Something along the lines of: "Listen, casey. This nanny story is not gonna' fly. It does not look good for you right now with what we have. I need something else." After she comes up with other options that are similarly stupid and he keeps saying they won't fly, she outs with it. "Ok, listen. Caylee is dead." "Do you know where she is. I need to know where the body is so I can monitor our chances of her being found. If her body is found, it will be much worse for you!" "She's around Suburban Drive by the school."
Now, the fictional questioning by JB I just proposed is a techinque I know that some defense attorneys use, not necessarily to get their clients to fully confess, but to either suggest to them to come up with a more plausible theory or to suggest to them, subtly, to admit to a lesser evil, like an accident, etc. It is very important for many defense attorneys to keep up with the fiction that the client is innocent of the charge, even between the attorney and client, because that allows them to sleep at night as well as not fall into the ethics trap of having to propose a scenario they know is 100% false. It is also important for clients to keep up the fiction, even when they know their attorney will not tell on them. It's just a dance some defendants and their attorneys do.
Also, the attorney does not want to create a new scenario for the client. They want the client to come up with it on their own. But, they need to subtly encourage the client to keep trying. Sometimes, this effort is misinterpreted by the client and/or the client becomes frustrated and simply confesses, perhaps partially. In the fictional conversation I proposed above, notice that casey does not need to say, "I killed her." But simply, "She's dead." This allows the fiction to be somewhat maintained, even if only by a thread.
Anyhow, after such a possible conversation, JB might tell his PI's, "Look, you need to go to this certain area and tell me what you find. Caylee's body might be there. This is all covered under attorney-client privilege, okay?" Notice, he's not saying his client is guilty, or that she confessed, or where he got the info. And, he does not want the cops called if a body is found, nor would he likely disturb anything or tell anyone else what was found, except his associates.
In any case, that causes the PI's to search. The problem is I cannot get the two PI's straight. Which one originally worked for JB? Did either of these cats work for JB at anytime? If so, that could support this proposed theory of why they were there, looking.
Bottom line is casey would tell if she felt pressured somehow to do so, possibly, in the above-proposed scenario, because she can no longer think up another lie that would seem plausible, wants JB to know that and why, and wants him to thus figure out a new and improved lie, with his legal expertise, that will explain why Caylee is missing and why casey is not to blame.