If he has evidence he had better release it quickly- not slowly.
Never ANNOUNCE you will prevent evidence that will bring someone down... just present the evidence.
Unless you want to become a target.
This is why I doubt the whole thing. What would be more credible is if they announced this after arrests had been made.. THEN I would think there was something to it.
AND.... if the witness is credible per the story suggested, the two implicated in the crime already know who the witness is.