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

Donald Trump's former personal attorney and fixer Michael Cohen said the ex-president is likely "seething" over the indictment because he's "never been held accountable."

"The fact that he is being held accountable, something that he has no desire to ever be. He's never been held accountable," Cohen told ABC News' George Stephanopoulos in an interview Friday on "Good Morning America."

"This is a man who held up the Bible and said he's never apologized to God because he's never done anything wrong," he added. "He doesn't understand accountability. And right now, [Manhattan District Attorney] Alvin Bragg has finally put that into his lap."

Cohen, who is now estranged from Trump and is a key prosecution witness, said he decided years ago that his "loyalty can no longer be to a man who doesn't deserve it."

Cohen was sentenced to three years in prison in December 2018, after pleading guilty to violating federal campaign finance law in connection with hush-money payments and lying to Congress, among other crimes.

During Friday's interview on "GMA," Cohen said he followed Trump's "message" for more than a decade and "that is what got me in trouble."

When asked if he feels ready to be cross-examined, Cohen replied: "Absolutely."

"The documents will speak for themselves," he added, referring to the sealed indictment.

"So, not just your testimony?" Stephanopoulos responded.

"No," Cohen said. "And it's also corroborating testimony, but it's documents."