If this was the most credible lead they've had so far,then maybe their lead criteria needs re-evaluated.They went on the word of a brokester has-been.Zerilli wasn't in on the hit, but he convinced the Feds that the hearsay he was offering was gold.

The original case agent didn't believe him,and said so.Zerilli just released an online manuscript,at the urging of his wife,so what better blitz advertising? Actually Zerilli is pretty slick.
He sells a book without having to print it, and gets publicity for it without buying ad time. Maybe he picks up a few Media appearances.
I think the most telling item is that the paperwork that the FBI filed in support of the search warrant is still "under seal".