For months, federal prosecutors have brought witnesses in front of a grand jury in Washington, DC, to investigate efforts by former President Donald Trump and his close allies to reverse the results of the 2020 presidential election.
The witnesses, several of whom appeared under subpoena, range from low-level aides to Trump's own vice president. There are also several key witnesses who have met with prosecutors for interviews that could help special counsel Jack Smith build his case.
Any indictment that comes from the sprawling probe into aftermath of the election, efforts to overturn the result or the January 6, 2021, attack at the US Capitol will likely rely, at least in part, on what those individuals testified to under oath behind closed doors.
Here's who's appeared before the grand jury or spoken with prosecutors:
Witnesses who have testified before the grand jury
Mike Pence
Former Vice President Mike Pence testified in April -- the first time in modern history that a vice president has been compelled to testify about the president he served beside.
Pence testified for over five hours and was likely asked to recount his direct conversations with Trump leading up to January 6, 2021, and Trump's unsuccessfully attempt to pressure him into blocking the 2020 election's result.
Both Pence and Trump asked for the subpoena to be thrown out, but trial and appellate judges rejected that request.
Mark Meadows
Mark Meadows, Trump's former chief of staff, appeared before the grand jury in June.
He was also ordered by a judge to provide documents to investigators despite claims of executive privilege.
As chief of staff, Meadows was in the middle of Trump's efforts to overturn the election in the two months between Election Day and Joe Biden's inauguration. Meadows pushed Justice Department officials to investigate debunked claims of voter fraud and communicated with Trump's allies about plans to challenge Biden's win.
Marc Short
Marc Short, former chief of staff to Pence, testified to the grand jury about the fake elector scheme and the role of Trump lawyers John Eastman and Rudy Giuliani.
Greg Jacob
Greg Jacob, a former aide to Pence, was also questioned about the scheme to appoint fake electors in battleground states.
Short and Jacob, both members of Pence's inner circle, were present in key meetings in the lead-up to the January 6 riot that were part of a pressure campaign to convince Pence to disrupt Congress' certification of Biden's electoral win.
Dan Scavino
Former White House deputy chief of staff Dan Scavino testified to the grand jury twice -- before and after a court decision that he cannot withhold answers on presidential secrecy grounds.
Pat Cipollone
Former Trump White House counsel Pat Cipollone testified twice to the grand jury for several hours. Cipollone repeatedly opposed efforts to overturn the 2020 election.
Patrick Philbin
Patrick Philbin, Cipollone's deputy, also testified twice. He and Cipollone pushed back several occasions, including a proposal to replace the attorney general with someone willing to look into false claims of election fraud.
Stephen Miller
Stephen Miller, a former White House speechwriter and senior adviser to Trump, gave testimony in November that could provide a first-hand account of the former president's preparations for his infamous speech at the Ellipse in Washington on January 6.
Miller was the first known witness to testify under the purview of special counsel Jack Smith.
Ken Cuccinelli
Former Department of Homeland Security official Ken Cuccinelli testified in January. As a top figure at DHS, Cuccinelli fielded and inquiry from Trump and his top advisers about the executive branch seizing voting machines.
Trump also considered appointing Cuccinelli to a special position after the election to root out election fraud on behalf of the White House, according to a Senate Judiciary Committee report.
John Ratcliffe
Former Director of National Intelligence John Ratcliffe, who CNN has reported personally told Trump and his allies that there was no evidence of foreign election interference or widespread fraud, testified in April.
Newt Gingrich
Former Republican House Speaker Newt Gingrich allegedly communicated with senior advisers to Trump about television advertisements that relied on false claims of election fraud, according to the according to the House select committee, and joined efforts to submit fake slates of electors in battleground states that Trump lost.
He appeared in front of a grand jury in June.
Nick Luna
Former White House aide Nick Luna served as Trump's bodyman, putting him by the president's side during critical meetings leading up to the election as well as with him throughout the day on January 6, 2021.
John McEntee
As director of the White House Presidential Personnel Office and an aide to the former president, John McEntee was in several small and potentially critical meetings around the election and may be able to shed light on Trump's thinking at the time.
Beau Harrison
Beau Harrison was also an aide to Trump.
William Russell
William Russell, a former White House special assistant and deputy director of presidential advance, testified twice to the grand jury.
Michael McDonald
Michael McDonald is the chairman of the Nevada Republican Party and was allegedly one of the fake electors appointed in that state. McDonald was given limited immunity to testify.
Jim DeGraffenreid
Jim DeGraffenreid, another Nevada GOP official and Trump elector, was also given limited immunity to testify.
G. Michael Brown
As a Trump campaign election day operations official, Gary Michael Brown allegedly told campaign staff he delivered fake elector votes for Trump from battleground states to Congress.
Ali Alexander
Ali Alexander was the leader of the "Stop the Steal" group who helped to organize rallies before the US Capitol attack. He testified before a grand jury last summer.
Secret Service agents
Several US Secret Service agents on Trump's detail have also testified.
People who were interviewed by prosecutors or investigators
Some witnesses did not appear before a grand jury and were instead interviewed by FBI agents, investigators, or prosecutors with the special counsel's office.
Despite taking place in private, these interviews can be just a vital to a criminal investigation. Investigators generate an official report from each interview and can read information from these interviews to a grand jury to become part of the case's record.
Here is a list of the people who have sat for an interview:
Rusty Bowers
Rusty Bowers was a top Republican official in Arizona who rejected pressure from Trump and his allies in the aftermath of the 2020 election.
Bowers told CNN that he spoke with investigators about a call he had with both Trump and Giuliani after the election, and a second call with Trump alone
Bowers added that probe appeared very broad, and that investigators knew "a lot of information about attorneys that work with them. About Mr. Giuliani that made the calls and visited us. And other members of his team, who they were, when the meetings were, what was discussed in those meetings or in that meeting."
Brad Raffensperger
Georgia Secretary of State Raffensperger was interviewed by the special counsel's office in late June, CNN has reported.
As part of the discussion, investigators likely questioned Raffensperger about a January 2021 phone call where Trump to pressed Raffensperger to "find" the votes needed for Trump to win the state of Georgia.
Cassidy Hutchinson
Cassidy Hutchinson was a trusted aide to Meadows, and her surprise bombshell testimony to the House select committee gave the American public insight into what she witnessed in the West Wing during the final weeks of the Trump administration.
In public testimony before the January 6 committee this summer, she recounted how Trump and his inner circle were warned about the potential for violence on January 6 and alleged that the former president wanted to join the throngs of his supporters at the Capitol.
Alyssa Farah Griffin
Alyssa Farah Griffin, a former White House communications director during the Trump administration who is now a CNN political commentator, voluntarily met with investigators in June.
The interview was focused primarily on Trump's state of mind, what he knew about the baseless claims of widespread election fraud he was pushing leading up to the January 6 attack, efforts to pressure then-vice president Pence to overturn the election results, and the role of former White House chief of staff Mark Meadows.
Chad Wolf
Chad Wolf, the one-time acting secretary of the Department of Homeland Security, met with FBI officials and Justice Department prosecutors after receiving a grand jury subpoena.
Wolf told prosecutors that after the 2020 election he was asked by White House officials if DHS had legal authority to seize voting machines and each time he said no, according to his attorney.
Robert O'Brien
National security adviser Robert O'Brien also recounted to investigators earlier this year conversations about seizing voting machines, including during a heated Oval Office meeting that Trump participated in.
Rudy Giuliani
Rudy Giuliani, Trump's former attorney, played a key role in the plot to appoint fake electors in battleground states as part of an effort to usurp Biden's electoral college victory.
The special counsel's office has also shown interest in several members of Trump's post-election legal team, including Giuliani, who tried to help Trump's push to use the department to overturn the election.
Mike Roman
CNN reported that Mike Roman, a former Trump campaign official, has struck a deal with investigators to sit for an interview. Roman was involved in efforts to put forward slates of fake Trump electors following the 2020 election.
Boris Epshteyn
Epshteyn works as an attorney and adviser to Trump. Epshteyn was a special assistant to Trump at the White House and advised Trump during the 2020 campaign.
Fake electors in battleground states
Investigators have spoken to several individuals in battleground states --- including Georgia and Michigan -- who were recruited to be part of the fake electors plot but backed out before the election was certified.