They certainly do!! Since this PRELIMINARY report, they have tested, retested, cross-tested, and have done the most intense tests that science will allow to determine it was Caylee's body in the trunk before they charged Casey with First Degree Murder and Aggravated Manslaughter. The tests PROVE it and they will prove it in court.
The chances are excellent they will find Caylee's remains this weekend. Given Casey's locations during the time after she went missing and the various places they are searching, Caylee HAS to be in one of them since Casey never left Orlando. Logic will prevail in this case and TES along with OCSO have come to the logical conclusion of where she mostly likely buried or dumped Caylee.
I have complete faith they know what they are doing and with the searchers in the thousands this weekend...they stand a much better chance of bringing Caylee home. Godspeed.