“Mueller would know that trying to interview Ivanka Trump would be like lighting a match to the highly combustible Donald Trump,” said Elizabeth de la Vega, a former federal prosecutor who reported directly to Mueller when he served in the U.S. attorney’s office in the Northern District of California. “The team would want to wait to the last possible moment, if at all, before taking that step.”

Calling in Ivanka Trump for an interview, former Justice Department officials and legal experts said, would be risky primarily for two reasons: It would give the public the perception that the prolonged investigation has reached the point of harassing the president’s family members, giving Trump more ammunition to decry how unfairly he and his family are being treated in an investigation he has already deemed a “witch hunt.”

And it would carry with it the very real possibility that the reactive president would “go nuclear,” according to a former federal prosecutor, once again raising the possibility of pardons or toying with the idea of firing the special counsel altogether.