The prosecution of the nephews of Venezuela's first lady has taken a blow as the U.S. government told its star witness his cooperation deal is getting torn up for his lies.

The surprise twist in the drug trial of Efrain Campo and Francisco Flores came Tuesday in Manhattan federal court.

The turn came after a defense lawyer used recorded prison conversations to try to show jurors the cooperator was violating his deal with prosecutors. The recorded conversations suggest the informant was communicating about drug deals and breaking prison rules.

Assistant U.S. Attorney Brendan Quigley confronted the cooperator, asking if he understood that his cooperation agreement was getting "ripped up."

The cooperator — Jose Santos-Pena — responded "no sir."

The prosecutor countered: "You should."