The House committee investigating the January 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 US Capitol.

The January 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.

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Chairman Rep. Bennie Thompson and vice-chair Rep. Liz Cheney 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 overturn Joe Biden’s election victory posed a grave threat to democracy.

Stepien, a longtime Trump ally, oversaw the “conversion” of Trump’s presidential campaign to a “Stop the Steal” effort, according to a subpoena issued by the committee last fall. He is likely to face questions about what those in Trump’s inner circle were telling the president about the election results. Stepien 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 closely involved in election night coverage who stood by the decision to declare Arizona as being won by Biden. He wrote about his experiences later in an op-ed and might be asked about Trump’s actions as Fox News declared states Biden won.

The second group of witnesses testifying Monday will consist 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 US norms.

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Among them is the former US attorney in Atlanta, BJay Pak, who abruptly resigned after Trump pressured Georgia state officials to overturn his presidential defeat. Trump wanted to fire Pak as disloyal, but Pak stepped down after Trump’s call urging Georgia Secretary of State Brad Raffensperger to “find” enough votes to overturn Biden’s win in the state became public.

The panel will also hear from former Philadelphia City Commissioner Al Schmidt, the only Republican on the election board and who faced criticism as the state’s election was called for Biden; and noted Washington attorney and elections lawyer Benjamin Ginsberg.