Former President Donald Trump is expected to travel to New York on Monday, sources familiar with the matter told ABC News.

He is expected to appear in court on Tuesday at the earliest, the sources said, on what is expected to be around two dozen counts - including felonies.

The exact charges are unknown since the indictment will not be unsealed until Trump appears in court.

-ABC News’ Aaron Katersky, Katherine Faulders, John Santucci

As legal experts speculate on what charges lay inside the sealed indictment ahead of former President Donald Trump's expected surrender on Tuesday afternoon, many predict that prosecutors could try out a new legal theory to justify bringing the charges.

"This could be a novel legal theory," said Kate Shaw, a law professor at Cardozo and ABC News contributor, speculating on what charges the public could see against Trump while stressing it's unknown until the indictment is unsealed.

Read more here.

-ABC News' Libby Cathey

Former President Donald Trump has been charged with around two dozen counts, including felonies, sources familiar with the sealed indictment told ABC News.

The exact charges remain unknown since the indictment will not be unsealed until Trump appears in court on Tuesday.

The Manhattan district attorney’s office declined to comment.

The Senate sergeant at arms is warning of potential demonstration activity related to the indictment of former President Donald Trump.

"While law enforcement is not tracking any specific, credible threats against the Capitol or state offices, there is potential for demonstration activity," an email obtained by ABC News said.

Capitol Police "is working with law enforcement partners, so you may observe a greater law enforcement presence on Capitol Hill," the email said, adding that there could be "nationwide impacts to Senate state offices."

The Capitol Police declined to comment and the sergeant at arms didn't immediately respond to ABC News' request for comment.

-ABC News' Luke Barr

Criminal prosecution proceedings typically start with an arrest and a court appearance, but legal experts say that on many occasions, especially in white collar crimes, suspects aren't hit with charges or a visit from an officer until long after an official investigation is underway.

Typically, if a crime is being investigated, law enforcement agents will make an arrest, file initial charges and bring a suspect to be arraigned in court, Vincent Southerland, an assistant professor of clinical law and the director of the criminal defense and reentry clinic at NYU School of Law, told ABC News.

After this arraignment, prosecutors would impanel a grand jury for a formal criminal indictment. Southerland, who has been practicing law in New York state for 19 years, said this process includes giving the jury evidence, possible testimony and other exhibits before they can officially charge a person with felonies.

A Manhattan grand jury is currently investigating Trump's possible role in the hush payment to adult film actress Stormy Daniels. The former president has denied any wrongdoing and having an affair with Daniels. His attorneys have framed the funds as a response to an extortion plot.

-ABC News' Ivan Pereira