That's easy in this particular case - the U.S. Marshalls are selling it, and presumably they're not lying about it. Maybe the U.S. police is
that corrupt, but I think somebody would find out sooner or later (they would need to make them somewhere, a
large order of custom Fyre-branded hats by the U.S. Marshalls is not an everyday thing), and that would be an obvious case of fraud then.
On the other hand yeah, members of the U.S. services tried to steal the Silk road bitcoin too, so who knows.