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.

However, Southerland noted that prosecutors can start with the criminal indictment process in the beginning, especially if their case needs more evidence to press those charges.

Cheryl Bader, an associate clinical professor of law at Fordham University, told ABC News that such a move is common in white-collar criminal investigations that involve looking at delicate nuances in the state law and require more time.

Bader said investigations into prominent figures, such as the current investigation by the Manhattan district attorney's office into former President Donald Trump, also prompt prosecutors' offices to make their case to the grand jury in the most meticulous and thorough way possible.

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-ABC News' Ivan Pereira

The Democratic National Committee said in a statement Thursday, “No matter what happens in Trump’s upcoming legal proceedings, it’s obvious the Republican Party remains firmly in the hold of Donald Trump and MAGA Republicans."

The DNC vowed, "We will continue to hold Trump and all Republican candidates accountable for the extreme MAGA agenda that includes banning abortion, cutting Social Security and Medicare, and undermining free and fair elections.”

Former President Donald Trump can still be elected president -- even if he is convicted -- experts tell ABC News. But there are practical reasons that could make it a challenge, experts say.

Trump said recently at the annual Conservative Political Action Conference that he would "absolutely" stay in the race for president even if he were to be criminally indicted.

Trump has denied wrongdoing and has characterized the probe as part of a "witch hunt" against him.

The U.S. Constitution does not list the absence of a criminal record as a qualification for the presidency.

Constitutional experts also told ABC News that previous Supreme Court rulings hold that Congress cannot add qualifications to the office of the president. In addition, a state cannot prohibit indicted or convicted felons from running for federal office.

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-ABC News' Laura Romero

Former President Donald Trump told ABC News over the phone that the indictment is "an attack on our country."

He called it a "political persecution," adding, "They are trying to impact an election."

Trump in a statement Thursday called himself a "completely innocent person" facing "an act of blatant Election Interference."

Trump said, "Our Movement, and our Party - united and strong - will first defeat [Manhattan District Attorney] Alvin Bragg, and then we will defeat Joe Biden, and we are going to throw every last one of these Crooked Democrats out of office so we can MAKE AMERICA GREAT AGAIN!”

Trump's attorneys said in a statement Thursday, "He did not commit any crime. We will vigorously fight this political prosecution in Court."

Trump's son, Donald Trump Jr., said on his podcast Thursday, "This is weaponized justice at its worst."

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.

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-ABC News' Libby Cathey