Updated

A figure from the Whitewater investigation of President Bill Clinton said Tuesday that a former campaign aide to President Donald Trump should prepare to testify before a grand jury despite his off-and-on threats about defying a subpoena.

Sam Nunberg said for a time Monday he would defy special counsel Robert Mueller, but by the end of the day said he would likely cooperate with a probe. In some interviews, he said there may be incriminating evidence against the president.

Susan McDougal, who spent 18 months in jail for civil contempt after prosecutors said she didn't testify honestly before a grand jury, told The Associated Press on Tuesday that Nunberg's appearance before a grand jury is virtually assured because of his remarks.

"I would say that by the time you have talked about the guilt of so many people on television, they will want to hear from you," McDougal said. "That ship has sailed. It is over. You are done. They will be talking to you and you will be showing up."

A jury convicted McDougal, her husband and a sitting Arkansas governor of fraud during a 1996 trial.

McDougal, who is now the associate director of pastoral services at the University of Arkansas for Medical Sciences, said that throughout the Whitewater investigation prosecutor Ken Starr had threatened her with incarceration.

"He said, 'You are going to go to jail for this,' and I said 'I'd be with better people,'" McDougal said.