PHILADELPHIA (WPVI) -- The House committee investigating the Jan. 6 riot is delving deeper into what it calls "the big lie," Donald Trump's false claims of voter fraud that fueled his relentless effort to overturn the 2020 election and led a mob of his supporters to lay siege to the U.S. Capitol.
The 1/6 panel resumes its hearings Monday with live witnesses, including Trump's campaign manager, Bill Stepien, as committee members say they have uncovered enough evidence for the Justice Department to consider an unprecedented criminal indictment against the former president. Stepien was subpoenaed for his public testimony.
Chairman Rep. Bennie Thompson, D-Miss., and vice chair Rep. Liz Cheney, R-Wyo., are set to lead the morning hearing after last week's blockbuster session drew nearly 20 million Americans to see its prime-time findings.
For the past year, the committee has been investigating the most violent attack on the Capitol since the War of 1812 to ensure such an assault never happens again. Its findings come as Trump is considering another run for the White House, and some warn that his effort to over turn Joe Biden's election victory posed a grave threat to democracy.
Stepien, a longtime Trump ally, is likely to face questions about what those in Trump's inner circle were telling the president as the election results rolled in. He is now a top campaign adviser to the Trump-endorsed House candidate, Harriet Hageman, who is challenging Cheney in the Wyoming Republican primary election.
In addition to Stepien, the committee is also set to hear testimony from Chris Stirewalt, a former Fox News political editor who had a front-row seat to election night coverage. He might be asked about Trump's actions as Fox declared various states being won by Biden.
A second group of witnesses testifying Monday will be made up of election officials, investigators and experts who are likely to discuss Trump's responses to the election, including dozens of failed court challenges, and how his actions diverged from U.S. norms.
The three scheduled to testify are the former U.S. attorney in Atlanta, BJay Pak, whom Trump viewed as disloyal and wanted fired; former Philadelphia City Commissioner Al Schmidt, the only Republican on the election board and who faced down criticism as the state's election was called for Biden; and noted Washington attorney and elections lawyer Benjamin Ginsberg.
As he mulls a White House run, Trump is decrying the investigation into his efforts to overturn Biden's election a "witch hunt." He said last week that Jan. 6 "represented the greatest movement in the history of our country."
Nine people died in the riot and its aftermath, including a Trump supporter shot and killed by police. More than 800 people have been arrested in the siege, and members of two extremist groups have been indicted on rare sedition charges over their roles leading the charge into the Capitol.
SEE ALSO: Capitol riot panel blames Former President Trump for January 6 'attempted coup'
In its prime-time hearing, the committee laid out how Trump was told over and over again by his trusted aides and officials at the highest levels of government that there was no election fraud on a scale that could have changed the outcome. But Trump pursued his false claims about the election and beckoned supporters to Washington on Jan. 6 to overturn Biden's victory as Congress was set to certify the Electoral College results.
Additional evidence is set to be released in hearings this week focusing on Trump's decision to ignore the outcome of the election and the court cases that ruled against him.
Monday's hearing will also turn to the millions of dollars Trump's team brought in fundraising in the run-up to Jan. 6, according to a committee aide who insisted on anonymity to discuss the details.
SEE ALSO: Just before Jan. 6 hearing, 3 Capitol rioters express regret, ask for mercy
The committee has said most of those interviewed in the investigation are coming forward voluntarily, although some have wanted subpoenas to appear in public. It is unclear why Stepien was issued a subpoena. A Trump spokesman, Taylor Budowich, suggested that the committee's decision to call Stepien was politically motivated.
Lawmakers indicated that perhaps their most important audience member over the course of the hearings may be Attorney General Merrick Garland, who must decide whether his department can and should prosecute Trump. They left no doubt as to their own view whether the evidence is sufficient to proceed.
Rep. Jamie Raskin, D-Md., said on CNN he doesn't intend to "browbeat" Garland but noted the committee has already laid out in legal pleadings criminal statutes they believe Trump violated.
"I think that he knows, his staff knows, the U.S. attorneys know, what's at stake here," Raskin said.
No president or ex-president has ever been indicted. Garland has not specified whether he would be willing to prosecute, which would be complicated in a political election season in which Trump has openly flirted with the idea of running for president again.
The Associated Press contributed to this report.