It’s unclear what Nader told Mueller, though it’s believed his testimony pertained to actions by Erik Prince, the Blackwater founder and brother of Betsy Devoes, who Mueller alleged met with an ally of Russian President Vladimir Putin in the Seychelles around the time of Trump’s inauguration. It was alleged that Prince was trying to set up a “back channel” to Trump. Nader is allegedly an emissary of the UAE.
Soon after the images were discovered, prosecutors reportedly filed a criminal complaint against Nader over the images, but they kept the charges under seal, and Nader’s lawyers were never informed of his impending arrest all the while that he continued to cooperate with the Mueller probe.
That means that Mueller kept a suspected child abuser and pornographer on the streets while it used him as a witness. And now that Nader is no longer useful, he is finally being charged.