After a years-long investigation from Manhattan prosecutors into what they call the former President's role in a hush money scheme and coverup.
NBC News is reporting it learned a new witness will testify before the New York grand jury today.
Attorney Robert Costello was once a legal advisor to Michael Cohen. Cohen told NBC News he is standing by as a rebuttal witness.
Mr. Trump is attacking Manhattan DA Alvin Bragg's investigation of 2016 hush money payments to adult film star Stormy Daniels as, "prosecutorial misconduct and interference with an election."
Bragg then sent a letter to his staff saying, "safety is our top priority," and that the DA would, "not tolerate attempts to intimidate our office or threaten the rule of law in New York."
"In this great country of ours, no one is above the law...I would urge everyone to allow the prosecutors to do their job,” Democratic New York House minority leader Hakeem Jefferies said.
Democrats are also demanding Mr. Trump tone down his rhetoric as the legal process unfolds. If the former President is indicted, it would mark a historic first.
There is a protest planned in lower Manhattan today in response to the announcement. NYPD said it could deploy hundreds of officers as needed to keep the city safe.