I wish I would have heard that particular show. I have great respect for Van Susteren's legal expertise, but I can't think what possible statute the feds would have used to charge Joran with murder here in the states.
While the US does assert extraterritorial jurisdiction in some crimes (mostly terrorism, and some crimes related to MEJA), simple murder isn't one of them.
If Joran took her in a boat and traveled outside the territorial waters of Aruba, and the feds could prove it, then they'd have a case as US Code does give the DOJ tremendous latitude for prosecuting crimes on the open seas.
Instead, Van Susteren was suggesting that the FBI waited too long, or that the Arubans tipped off van der Sloot that the FBI was coming, and he fled before the FBI could act.
Here's the transcript of the Greta show.
-PJ