The indictment of Donald Trump marks an unprecedented development in the country's history -- the first time a former president has ever faced criminal charges.

Historians say that not since Richard Nixon had there been the real prospect of a commander-in-chief being formally accused of a crime, though Nixon avoided that fate after being pardoned by successor Gerald Ford.

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-ABC News' Tal Axelrod

Republican National Committee Chairwoman Ronna McDaniel called the indictment "a blatant abuse of power from a DA focused on political vengeance."

"When our justice system is weaponized as a political tool, it endangers all of us," she tweeted.

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.”

Manhattan District Attorney Alvin Bragg on Friday again resisted the House GOP investigation of his office’s prosecution of Trump.

Bragg’s legal counsel called the inquiry “illegitimate incursion” into a legitimate investigation.

The House Republicans -- Reps. Jim Jordan, James Comer and Bryan Steil -- have said they want to find evidence of federal funds used to investigate Trump. But Bragg’s office said they were merely doing Trump’s bidding.

“Finally, as you are no doubt aware, former President Trump has directed harsh invective against District Attorney Bragg and threatened on social media that his arrest or indictment in New York may unleash 'death & destruction.' As Committee Chairmen, you could use the stature of your office to denounce these attacks and urge respect for the fairness of our justice system and for the work of the impartial grand jury," counsel Leslie Dubeck wrote in a letter to the lawmakers.

"Instead, you and many of your colleagues have chosen to collaborate with Mr. Trump’s efforts to vilify and denigrate the integrity of elected state prosecutors and trial judges and made unfounded allegations that the Office’s investigation, conducted via an independent grand jury of average citizens serving New York State, is politically motivated.”