Former President Donald Trump is facing a potential fourth indictment, this time in Georgia, where state prosecutors may soon bring charges over his attempts to overturn the 2020 election results there.

Fulton County District Attorney Fani Willis, a Democrat, launched the probe in early 2021 and has investigated Trump's attempts to pressure Georgia officials into interfering with the vote tally, the "fake electors" scheme to subvert the Electoral College and other efforts to undo the will of the voters.

Many of these incidents also factored into Trump's federal indictment on charges related to the 2020 election aftermath. (Trump pleaded not guilty last week to four federal charges in that case.) That probe, led by special counsel Jack Smith, is separate from the state-level inquiry in Georgia.

Willis is expected to spend one or two days presenting her case before a grand jury next week, likely starting Monday. At least two witnesses have publicly confirmed that they were called to testify in front of the grand jury Tuesday.

Trump has vehemently denied wrongdoing, as have his allies who are also under scrutiny in the probe. The former president has lashed out at Willis, who is Black, calling her "racist" and a "lunatic Marxist."

Here's what to know about the investigation.

What is being investigated?

Candidate Joe Biden beat Trump in Georgia by 11,779 votes, or about 0.23% of nearly 5 million ballots cast. Biden's razor-thin victory was confirmed by two recounts and certified by Gov. Brian Kemp and Secretary of State Brad Raffensperger, both Republicans.

Instead of conceding, Trump launched a multi-pronged effort to overturn the results, including a pressure campaign targeting key state officials. Trump wanted them to abuse their powers to "find" enough votes to flip the results, or to block Biden's victory from being certified. They refused.

"So look. All I want to do is this. I just want to find 11,780 votes, which is one more than we have. Because we won the state," Trump said in a phone call to Raffensperger on January 2, 2021.

When these efforts failed, Trump urged Georgia lawmakers to convene a special session of the GOP-run legislature so they could overturn Biden's victory. Trump allies, including his attorney Rudy Giuliani, presented bogus fraud claims to the state House and Senate at hearings in December 2020. The Trump campaign, with outside lawyers who supported their cause, filed meritless lawsuits that tried to overturn the Georgia results.

Trump's campaign also recruited a group of GOP activists in Georgia to serve as fake electors, who were part of a seven-state scheme to undermine the Electoral College. These fake slates of electors played a key role in Trump's ill-fated plot to stop Congress from certifying Biden's victory on January 6, 2021.

At the same time, Trump tried to weaponize the Justice Department to help him intervene in Georgia and elsewhere. He tried to cajole top Justice Department officials and federal prosecutors in Atlanta into falsely announcing that the election was "corrupt" and that Biden's win was tainted by massive fraud.

There were also efforts by Trump supporters to breach a voting system in Georgia, in hopes of proving that the election was rigged. Some Trump supporters also allegedly tried to intimidate a Fulton County election worker into falsely admitting she was part of a massive anti-Trump fraud scheme in 2020.

Who might be indicted?

Trump is obviously at the center of the probe. The foreperson of the special grand jury that previously heard evidence in the case suggested in a series of interviews that the panel recommended charges against Trump, and that there was a long list of potential co-defendants. CNN recently reported that Willis is expected to seek more than a dozen indictments.

Prosecutors have notified some key players that they are targets of the investigation. This includes Giuliani, who was an unindicted co-conspirator in Trump's federal indictment on 2020-related charges.

The 16 Republican activists who served as fake electors, including the chair of the Georgia Republican Party, also got target letters, though some decided to cooperate with prosecutors.

Which crimes might be charged?

Earlier in the investigation, Willis said her team was investigating a wide array of potential crimes. This included solicitation of election fraud, making false statements to state and local government bodies, conspiracy, racketeering, violation of an oath-of-office, and involvement in election-related threats.

CNN reported in March that prosecutors were eying racketeering and conspiracy charges. Willis has previously used Georgia's state RICO laws -- which stands for "racketeer influenced and corrupt organizations" -- to prosecute gangs and even public school officials who oversaw a cheating scheme.

What is the process?

Willis' team is expected to spend one or two days presenting their case before the grand jury. To secure an indictment in the Trump investigation, 16 of the 23 voting grand jury members would need to be present. Once that quorum is established, 12 votes would be needed to hand up an indictment.

CNN has previously reported that some key witnesses were recently subpoenaed to appear, presumably as part of Willis' upcoming presentation. This includes former Georgia Lt. Gov. Geoff Duncan, a Republican who is now a CNN political contributor, and former state Sen. Jen Jordan, a Democrat.

Duncan told CNN's Fredricka Whitfield on Saturday that he had received a notice to testify in front of the grand jury Tuesday. Shortly after, independent journalist George Chidi, who had also been subpoenaed, shared on social media that he had also received a similar notice.

When a grand jury approves an indictment, a prosecutor and court officials typically walk the paperwork to the courtroom of the presiding Superior Court judge. That group then usually presents the stack of papers to the presiding judge, who reviews and signs them, and hands back the signed papers. The group then walks the signed indictments to the clerk's office, where case numbers are assigned.

Who is DA Fani Willis?

Willis was elected Fulton County district attorney in November 2020 after defeating her former boss, a six-term incumbent, in the Democratic primary earlier that year. She was sworn in on January 1, 2021, just one day before Trump's infamous call with Raffensperger.

She is the first woman to hold the post in Fulton County, which is home to most of Atlanta, and includes some of the nearby suburbs. (Biden won approximately 73% of the vote in Fulton County in 2020.) She is up for reelection next year, so she might be leading an historic trial while also campaigning for votes.

Asked by CNN in 2022 about potentially prosecuting a former president, she said, "What I could envision is that we actually live in a society where Lady Justice is blind, and that it doesn't matter if you're rich poor, Black, White, Democrat or Republican. If you violated the law, you're going to be charged."

Trump has hammered Willis throughout the process, accusing her of partisan bias and claiming she is only pursuing the probe to fuel her future political ambitions. His critiques are largely unsupported, though Willis made a significant misstep last year, when she hosted a fundraiser for the Democratic opponent of one of the people she was investigating, Georgia Lt. Gov. Burt Jones, a Republican.

Jones -- who was one of the fake electors in Georgia -- successfully sought a court order blocking Willis from further investigating him. Fulton County Superior Court Judge Robert McBurney, who issued the order, said it was a "'what are you thinking moment" for Willis and that "the optics are horrific."

But McBurney, who presided over the special grand jury and related matters, has also praised Willis' handling of the investigation. In a recent ruling in a related case, he contrasted her professional conduct with the "stream of personal invective flowing from" Trump and his lawyers.

"Put differently, the District Attorney's Office has been doing a fairly routine -- and legally unobjectionable -- job of public relations in a case that is anything but routine," McBurney wrote.

What about the federal case?

The federal election-subversion charges against Trump overlap with the Georgia probe in a big way, but the investigations are separate. If Trump is charged in Georgia, some procedural and logistical challenges may arise, such as deconflicting the schedule of the state case with the federal case.

If Trump wins the 2024 presidential election, he could order the Justice Department to drop the cases and could pardon himself.

But the Georgia case -- a state-level prosecution -- might still move forward.

How is Trump responding?

Trump has responded to the Georgia investigation with a steady stream of attacks against prosecutors, and by resurrecting many of his debunked lies that the 2020 election was rigged.

He has also repeatedly invoked race in his public rants against Willis. At a campaign rally Tuesday, Trump called Willis "a young woman, a young racist" and baselessly claimed she has ties to gang members.

Trump's lawyers tried to essentially neuter the probe -- by filing a motion with the judge who oversaw the special grand jury, and by separately asking the Georgia Supreme Court to intervene. They wanted a court order to block Willis from using the evidence she gathered in any future criminal or civil case. These legal moves were seen as a long shot, and they were rejected in the past few weeks.