Nearly a month after a pro-Trump mob violently stormed the U.S. Capitol, a clearer image is rising of the people and teams concerned as federal authorities arrest and cost individuals who allegedly participated in the riot.

Cynthia Miller-Idriss, a sociology professor at American University who research extremism and far-right actions, stated that those that stormed the Capitol are a “loose coalition” of teams from throughout the far-right spectrum.

“These were people who were radicalized and participated in an insurrection, it’s just that some did so in a very planned way, and I think others ended up being caught up spontaneously in mob rioting,” Miller-Idriss said.

For the experts, the most prominent force that unified hard-right adherent, militias and other Trump supporters and whipped them up into a frenzy behind the idea that the election was stolen — Trump himself.

And Trump, unlike past presidents, gave these disparate groups a national platform unlike any they’d had in modern American history with the instantaneous recognition and feedback of social media.

Trump’s false claims about election fraud and his rhetoric post-election urging his supporters to fight back is at the heart of the former president’s Senate impeachment trial, which is set to begin next week. The House of Representatives voted to impeach Trump on Jan. 13 after House Democrats filed an article of impeachment, charging him with “incitement of insurrection.”

ABC News reached out to the former president’s legal team but representatives declined to comment.

The makeup of the mob

Larry Rosenthal, chair and lead researcher of the Berkeley Center for Right-Wing Studies, said that the mob was generally made up of two groups: “right-wing populists,” whom he described as half of Trump’s most devoted “rally-goers,” and right-wing militia teams that characterize two overlapping “currents” of the far-right motion: white nationalism and anti-government.

Some of these ideologies and beliefs were on show in far-right insignia scattered amongst the crowd, which included symbols of the Confederacy, Nazism, white supremacy and anarchy.

And some of these arrested have documented their alleged involvement on social media and a few have recognized ties to far-right teams, or are adherents of disproven conspiracy theories.

In addition to a numerous and free coalition of teams concerned, the members of the mob had been additionally not racially and ethnically homogenous.

Although the majority of rioters at the “Stop the Steal” rally had been white, the Trump mob was “not a homogenous group of white nationalists,” Cristina Beltrán, a professor at New York University who studies race, ethnicity and American politics, said.

In fact, one of the organizers of “Stop the Steal” is far-right activist and conspiracy theorist Ali Alexander, who identifies as Arab and Black. “Blacks for Trump” indicators had been noticed in the crowd and a few Black and Latino individuals are actually needed by the FBI for his or her alleged involvement in the siege.

In order to know Trump’s help, “we must think in terms of multiracial whiteness,” Beltrán writes in a Washington Post op-ed: “Multiracial whiteness reflects an understanding of whiteness as a political color and not simply a racial identity — a discriminatory worldview in which feelings of freedom and belonging are produced through the persecution and dehumanization of others.”

The motivations of the mob

After weeks of listening to false claims from Trump and his allies that the election was stolen, 1000’s of the former president’s most loyal followers disrupted the certification of the 2020 election outcomes by breaching the U.S. Capitol and clashing with regulation enforcement in a violent siege that resulted in the demise of 5 folks.

“This insistence — and not just Trump’s, but other elected officials’ insistence on that narrative of disinformation and that false conspiracy about the election has played a huge role in mobilizing these people,” Miller-Idriss stated.

In reality, chants shouted by rioters and indicators noticed in the crowd intently mirrored Trump’s personal phrases.

For occasion, the rally was named “Stop the Steal,” a phrase the Trump appeared to experience and tweeted repeatedly earlier than his account was suspended; shortly after Trump urged supporters to march to the Capitol and “fight like hell,” rioters shouted “fight for Trump” as they violently breached regulation enforcement to enter the constructing; indicators studying “take back our country” and “Trump won the legal vote” had been noticed amongst rioters, reflecting language Trump has been utilizing for weeks on Twitter as he repeated his false claims that the election was stolen from him.

And lastly, after Trump continued to falsely declare that Vice President Mike Pence may refuse to ratify President Joe Biden’s 2020 win — however had declined to take action, chants of “Hang Mike Pence” had been heard amongst rioters and pictures casting Pence as a traitor had been scattered amongst the crowd.

“(Trump) was continuing to propagate and circulate and disseminate this information about the election in ways that posed an existential threat to them and made them feel that their democracy has been stolen,” Miller-Idriss stated.

“People move from radicalization into mobilization, to really believing that they are not only empowered to act, but compelled to do so.”

The leader of the mob

According to Rosenthal, far-right groups that subscribe to white nationalist ideologies have always existed in the United States and since the second era of the Ku Klux Klan in the 1920s and 30s they have generally existed on the fringes of society, but Trump gave them a place in national politics.

“Suddenly, in 2015 at the level of presidential politics, somebody is talking their language,” he added, pointing to Trump’s anti-immigrant and racially charged rhetoric.

During his presidency, Trump frequently failed to condemn white supremacists and far-right groups espousing hateful and disproven conspiracy theories. He also often galvanized their causes.

The “Stop the Steal” movement energized some of the same elements of the far-right movement in the U.S. that shaped the August 2017 “Unite the Right” rally in Charlottesville when hundreds of so-called alt-right groups took to the streets to violently protest the removal of Confederate monuments.

“The ‘Unite the Right’ [movement] failed. It did not create such a unified militia and the groups that put it together started falling apart among themselves … the alt-right kind of went into decline, but 2020 resurrected things,” Rosenthal said.

This past year, anti-lockdown and anti-mask demonstrations amid the COVID-19 pandemic “inflamed the anti-government” right-wing militia groups, while the Black Lives Matter protests that erupted over the summer following the police killing of George Floyd “activated the white nationalist side” of the far-right movement, Rosenthal added.

And Trump, who was outspoken on both issues, elevated these positions to the national stage, experts said.

As president, Trump repeatedly downplayed the pandemic, refused to implement a nationwide mask mandate, mostly refused to wear a mask himself and his administration frequently flouted federal safety guidelines meant to curb the crisis.

Meanwhile, during his 2020 campaign, Trump cast himself as the “law and order” candidate, slammed the Black Lives Matter movement, dismissed concerns surrounding systemic racism and police brutality and in a message to voters, he claimed that if he is not re-elected, crime and riots will overtake the suburbs.

During his final weeks in office, the coalition of far-right groups again found a common cause around the baseless cause that the election had been stolen or rigged.

The white nationalist and anti-government currents compounded in “Stop the Steal,” along with an important element of “fascist mobilizations,” Rosenthal said: “A devotion to a singular chief who can command their consideration.”

ABC News’ Alexander Mallin and John Santucci contributed to this report.