A US house committee has heard dramatic testimony from former White House aides and others about Donald Trump’s relentless efforts to overturn the 2020 election – and his encouragement of supporters who stormed the US Capitol bent on achieving his goal.

But the big question remains: Was any of it criminal?

Cassidy Hutchinson, an aide in Mr Trump’s White House, added fresh urgency to the question as she delivered explosive testimony about the former US president’s actions before and during the insurrection in Washington, DC, on January 6 2021.

She said Mr Trump was informed that there were armed protesters at his morning rally before he stood onstage and told them to “fight like hell” at the Capitol.

Cassidy Hutchinson
An interview with Cassidy Hutchinson, former aide to Trump White House chief of staff Mark Meadows (House Select Committee via AP)

Then he argued with his security detail, she said, trying to go with the crowd.

Mr Trump’s aides knew there could be legal consequences. Ms Hutchinson said White House counsel Pat Cipollone told her “we’re going to get charged with every crime imaginable” if Mr Trump had gone to the Capitol that day as US congress was certifying Joe Biden’s election win.

Mr Cipollone said Mr Trump could be exposing himself to obstruction of justice charges or defrauding the electoral count, she said.

On the heels of Ms Hutchinson’s public testimony, the US house committee issued a subpoena for Mr Cipollone, saying in a letter that while he had provided an “informal interview” on April 13, his refusal to provide on-the-record testimony made their subpoena necessary.

The US justice department has recently expanded its investigation into the January 6 attack, targeting some of Mr Trump’s allies in Washington and around the country who participated in his scheme to invalidate Mr Biden’s victory. But prosecutors have not indicated whether they will bring a case against the former president.

Cassidy Hutchinson
Ms Hutchinson testifies (AP)

Witnesses have testified that Mr Trump was repeatedly advised by campaign aides and top government officials that he had lost the election to Mr Biden and that his claims of widespread voter fraud were divorced from reality.

However, he pressed ahead, shouting the false allegations that culminated in the riot at the Capitol.

Still in office, he leaned on the justice department to get US government law enforcement officials to take up his cause.

He pressured individual states – asking Georgia’s secretary of state to “find” votes, for example – and vice president Mike Pence, who was presiding over the joint session of congress that day.

Ms Hutchinson testified that Mr Trump said he wanted metal detectors removed from the area near where he was delivering a speech on January 6.

He said it did not matter to him if the supporters, who were to head to the Capitol, were carrying weapons because they were not there to hurt him.

Donald Trump
A photo of Donald Trump backstage before he spoke at the January 6 rally is displayed at the hearing (AP)

Mr Trump took to his social media website on Tuesday to deny much of Ms Hutchinson’s testimony, which was based on both her own interactions with Mr Trump and information from others who talked to him that day.

The former president has not been charged, but legal experts believe the testimony, presuming it can be corroborated, does give prosecutors avenues to pursue.

US federal law, for instance, makes it a crime to incite, organise, encourage or promote a riot like the one that enveloped the Capitol.

But that is a high bar for prosecutors to clear. Mr Trump’s exhortation to “fight like hell” could be construed as a more general call to action. He was acquitted by the US senate of an incitement charge in his impeachment trial after the insurrection.

However, a federal judge in February, in rejecting a request by Mr Trump to dismiss conspiracy lawsuits from Democratic legislators and two Capitol Police officers, said Mr Trump’s words “plausibly” led to the riot.

And Ms Hutchinson’s first-hand account of hearing Mr Trump complain about metal detectors suggested he was aware that some supporters were capable of violence, but brushed it off.

A more likely option for prosecution, said Jimmy Gurule, a former federal prosecutor who is a Notre Dame law professor, would be to pursue a case that Mr Trump conspired to defraud the United States through his wide-ranging efforts to overturn the election and to obstruct the congressional proceeding at which the results were to be certified.

That broad statute was cited by the House committee when it asserted in a March legal filing that it had evidence Mr Trump had engaged in a “criminal conspiracy.”

“He was perpetuating the big lie. To what end? To remain in power and to prevent Biden from assuming the reins of the presidency,” Mr Gurule said. “It was fraud on the American people.”

It remains to be seen whether Mr Trump will face charges. The congressional hearings have produced explosive testimony, but the one-sided presentation of facts, with no opportunities for cross-examination of witnesses, is a far cry from the burden of proof and trial constraints in criminal prosecutions.

Video of Donald Trump
It remains to be seen if Mr Trump will be charged (AP)

One of the more striking accounts from Ms Hutchinson – that Mr Trump, irate at being driven to the White House instead of the Capitol on January 6, tried to grab at the steering wheel of his presidential vehicle – was something she heard second-hand, likely inadmissible before a jury.

There are clear signs prosecutors are moving beyond the rioters, serving subpoenas last week on multiple state Republican Party chairmen in examining a scheme by Trump allies to create slates of alternate, or fake, electors in an attempt to subvert the vote.

US attorney general Merrick Garland, a former federal appeals court judge and circumspect by nature, has pledged the justice department will hold accountable wrongdoers “at any level” – more than 800 people have been charged so far – but he has not said one way or another that he is considering a case against Mr Trump.

Some Democrats in US congress have been pressing Mr Garland to act. The January 6 committee itself could make a formal criminal referral based on its more than 1,000 interviews.

The justice department would not have to act on such a referral, but it has been pressuring the panel to hand over its interview transcripts as it weighs making its own case.

There is no legal bar to prosecuting Mr Trump as a former president. Since he is no longer in office, justice department legal opinions that shielded him from criminal charges no longer apply.