Donald Trump's indictment on 37 counts of mishandling classified documents at his Florida estate represents the most serious legal jeopardy so far for Trump, coming less than three months after he was charged in New York with 34 felony counts of falsifying business records.

Here's a look at the charges, the special counsel's investigation and how Trump's case differs from those of other politicians known to be in possession of classified documents:

WHAT ARE THE CHARGES?

Trump faces 37 counts related to the mishandling of classified documents, according to the indictment unsealed Friday. The charges include counts of retaining classified information, obstructing justice and making false statements, among other crimes.

Trump is accused of keeping documents related to "nuclear weaponry in the United States" and the "nuclear capabilities of a foreign country," along with documents from White House intelligence briefings, including some that detail the military capabilities of the U.S. and other countries, according to the indictment. Prosecutors alleged Trump showed off the documents to people who did not have security clearances to review them and later tried to conceal documents from his own lawyers as they sought to comply with federal demands to find and return documents.

The top charges carry a penalty of up to 20 years in prison.

After leaving office in 2021, the former president showed someone working for his political action committee a map that detailed a military operation in a foreign country, prosecutors allege in the document. On another occasion that year, Trump showed a writer, a publisher and two of his staffers, none of whom had security clearances, a military plan of attack.

HOW IS TRUMP REACTING?

Trump, on his Truth Social app on Thursday, called his indictment "a DARK DAY for the United States of America." In a video post, he said, "I'm innocent and we will prove that very, very soundly and hopefully very quickly." Within 20 minutes of breaking the news, his 2024 presidential campaign sent out a fundraising missive asking for financial support.

On Friday, he continued to post about it on social media, lashing out at the special counsel who investigated the case, seeking to blame President Joe Biden, labeling the investigation a "WITCH HUNT" and declaring, "I had nothing to hide, nor do I now."

WHAT HAPPENS NEXT?

The Justice Department unsealed the indictment Friday, the first time the department confirmed Trump was being charged with a crime. Special counsel Jack Smith, who filed the charges, made his first public statement Friday afternoon, saying in brief remarks to reporters in Washington that the country has "one set of laws and they apply to everyone." He said prosecutors would seek a speedy trial.

Trump is scheduled to appear in court Tuesday in South Florida. It wasn't immediately clear what the procedure would look like.

When he was charged by the Manhattan district attorney in the New York case, Trump surrendered to authorities, where he was booked behind closed doors and appeared in the courtroom, sitting with his lawyers at the defense table.

The Florida case was initially assigned to Judge Aileen Cannon, who was appointed to the bench by Trump and who previously granted his request for an independent arbiter to review documents obtained during an FBI search of his Florida estate.

HOW DID THIS CASE COME ABOUT?

Officials with the National Archives and Records Administration reached out to representatives for Trump in spring 2021 when they realized that important material from his time in office was missing.

According to the Presidential Records Act, White House documents are considered property of the U.S. government and must be preserved.

A Trump representative told the National Archives in December 2021 that presidential records had been found at Mar-a-Lago. In January 2022, the National Archives retrieved 15 boxes of documents from Trump's Florida home, later telling Justice Department officials that they contained "a lot" of classified material.

That May, the FBI and Justice Department issued a subpoena for remaining classified documents in Trump's possession. Investigators who went to visit the property weeks later to collect the records were given roughly three dozen documents and a sworn statement from Trump's lawyers attesting that the requested information had been returned.

But that assertion turned out to be false. With a search warrant, federal officials returned to Mar-a-Lago in August 2022 and seized more than 33 boxes and containers totaling 11,000 documents from a storage room and an office, including 100 classified documents.

In all, roughly 300 documents with classification markings, including some at the top-secret level, have been recovered from Trump since he left office in January 2021.

HOW DID A SPECIAL COUNSEL GET INVOLVED?

Last year, U.S. Attorney General Merrick Garland picked Jack Smith, a veteran war crimes prosecutor with a background in public corruption probes, to lead investigations into the presence of classified documents at Trump's Florida estate, as well as key aspects of a separate probe involving the Jan. 6, 2021, insurrection and efforts to undo the 2020 election.

Smith's appointment was a recognition by Garland of the politics involved in an investigation into a former president and current White House candidate. Garland himself was selected by Democratic President Joe Biden, whom Trump is seeking to challenge for the White House in 2024.

Special counsels are appointed in cases in which the Justice Department perceives itself as having a conflict or where it's deemed to be in the public interest to have someone outside the government come in and take responsibility for a matter.

According to the Code of Federal Regulations, a special counsel must have "a reputation for integrity and impartial decision making," as well as "an informed understanding of the criminal law and Department of Justice policies."

DIDN'T BIDEN AND FORMER VICE PRESIDENT MIKE PENCE HAVE CLASSIFIED DOCUMENTS, TOO?

Yes, but the circumstances of their cases are vastly different from those involving Trump.

After classified documents were found at Biden's think tank and Pence's Indiana home, their lawyers notified authorities and quickly arranged for them to be handed over. They also authorized other searches by federal authorities to search for additional documents.

There is no indication either was aware of the existence of the records before they were found, and no evidence has so far emerged that Biden or Pence sought to conceal the discoveries. That's important because the Justice Department historically looks for willfulness in deciding whether to bring criminal charges.

A special counsel was appointed earlier this year to probe how classified materials ended up at Biden's Delaware home and former office. But even if the Justice Department were to find Biden's case prosecutable on the evidence, its Office of Legal Counsel has concluded that a president is immune from prosecution during his time in office.

As for Pence, the Justice Department informed his legal team earlier this month that it would not be pursuing criminal charges against him over his handling of the documents.

DOES A FEDERAL INDICTMENT PREVENT TRUMP FROM RUNNING FOR PRESIDENT?

No. Neither the indictment itself nor a conviction would prevent Trump from running for or winning the presidency in 2024.

And as the New York case showed, criminal charges have historically been a boon to his fundraising. The campaign announced that it had raised over $4 million in the 24 hours after that indictment became public, far smashing its previous record after the FBI search of Trump's Mar-a-Lago club.

HOW ARE TRUMP'S REPUBLICAN RIVALS REACTING TO THE NEWS?

Many of Trump's challengers for the GOP nomination jumped to his defense after news of the indictment broke.

Florida Gov. Ron DeSantis, Trump's top rival for the 2024 nomination, accused the Justice Department of political bias in charging the former president.

"The weaponization of federal law enforcement represents a mortal threat to a free society," DeSantis tweeted. "We have for years witnessed an uneven application of the law depending upon political affiliation."

He questioned why the Justice Department had been "so zealous" in bringing charges against Trump and "so passive" about going after former Democratic presidential nominee Hillary Clinton or Biden's son Hunter.

Campaigning in New Hampshire on Friday, former Vice President Pence said he was "deeply troubled" to see the indictment because he believed it would further divide the nation. He also called on Garland to make the indictment public as soon as possible.

"You need to stand up and explain to us why this was necessary before the sun sets today," Pence said.

Trump's United Nations ambassador, Nikki Haley, also decried the indictment, saying, "This is not how justice should be pursued in our country."

"The American people are exhausted by the prosecutorial overreach, double standards and vendetta politics," she said Friday. "It's time to move beyond the endless drama and distractions."

Sen. Tim Scott of South Carolina said Thursday that he felt the justice system's "scales are weighted" based on politics. "In America, every single person is presumed innocent, not guilty," Scott said on Fox News, decrying "the weaponization of the Department of Justice against the former president."

Biotech entrepreneur and "anti-woke" activist Vivek Ramaswamy said the federal case was part of "an affront to every citizen." Reiterating his comments that he would pardon Trump, Ramaswamy called it "hypocritical for the DOJ to selectively prosecute Trump but not" Biden over his own classified documents case.

Former Arkansas Gov. Asa Hutchinson, who called for Trump to drop out of the race after the New York charges were filed, said the federal indictment marked "a sad day for our country" and "reaffirms the need for Donald Trump to respect the office and end his campaign."

Meg Kinnard and Michelle L. Price report for the Associated Press. AP writers Jill Colvin in Des Moines, Iowa, and Jonathan J. Cooper in Phoenix, Arizona, contributed to this report.

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