(NewsNation) — A Manhattan grand jury voted to indict former President Donald Trump Thursday in connection to his alleged role in a hush-money payment scheme.

The felony indictment, which remains under seal, will mark the first time a former president faces criminal charges. Those exact charges are still unknown but will likely be announced in the coming days.

The investigation dates back to 2016 when Trump allegedly directed his former lawyer Michael Cohen to pay off porn star Stormy Daniels who said she had an affair with the former president. Trump has repeatedly denied that claim.

Cohen pleaded guilty to violating federal campaign finance law in connection to the payment after giving Daniels $130,000 through a shell company that he set up.

Trump acknowledged that he paid Cohen a “monthly retainer” as part of an agreement to “stop the false and extortionist accusations” by Daniels but denied that it had anything to do with campaign funding.

Until now, Trump had avoided charges after federal prosecutors said his company “grossed up” Cohen’s reimbursement for “tax purposes” but ultimately decided against prosecuting the then-sitting president.

Legal experts NewsNation spoke to believe the case will be difficult to argue and rely on untested legal theories.

“This is not what the criminal justice system is supposed to be,” prominent attorney and former Harvard Law professor Alan Dershowitz told NewsNation’s Chris Cuomo. “It’s not supposed to be creative, it’s not supposed to bring different statutes together that have never been used against somebody.”

The prosecution’s key witness, Cohen, is a convicted felon and has previously lied to Congress.

Earlier this month, Trump took to Truth Social and called for protests on his behalf.

“THE FAR & AWAY LEADING REPUBLICAN CANDIDATE & FORMER PRESIDENT OF THE UNITED STATES OF AMERICA, WILL BE ARRESTED ON TUESDAY OF NEXT WEEK. PROTEST, TAKE OUR NATION BACK!” Trump wrote.

Thursday’s indictment marks the conclusion of an investigation the Manhattan District Attorney’s office has been looking into since 2019.

Manhattan DA Alvin Bragg, a Democrat, has been criticized by Republicans on Capitol Hill who say the hush money probe is politically motivated.

In a letter last week, House Judiciary Committee Chairman Jim Jordan (R-Ohio) said if Bragg were to prosecute Trump it would “erode confidence in the evenhanded application of justice” and “interfere in the course of the 2024 presidential election.”

Bragg has previously boasted about suing Trump or his administration more than 100 times during his tenure at the attorney general’s office.

Thursday’s criminal charges are just one part of the former president’s ongoing legal troubles. Trump also faces criminal probes into his mishandling of classified documents, alleged election interference in Georgia and his role in the events that transpired on January 6.