(CNN) Leaders of the right-wing extremist Proud Boys will face trial starting Monday for their alleged conspiracy to stop Joe Biden from assuming the presidency, another test for the Justice Department's effort to punish the far-right political movement connected to fierce allies of former President Donald Trump.
Federal prosecutors intend to prove that four leaders of the Proud Boys -- Enrique Tarrio, Ethan Nordean, Joseph Biggs, Zachary Rehl -- plotted and broadly encouraged violence in the build up to January 6.
When the riot, allegedly initiated by a member of the Proud Boys, broke out at the Capitol, Nordean, Biggs and Rehl stood back while others -- including the fifth defendant Dominic Pezzola -- took action, prosecutors argue.
To prove their case, prosecutors will likely feature the testimony of several Proud Boys who pleaded guilty to charges connected to the conspiracy including two alleged leaders and close allies of Tarrio. Prosecutors will also heavily depend on the defendants' own words in texts and social media posts, as well as recorded planning meetings and videos from the riot.
Attorneys for the five defendants have argued that they were merely protesting on January 6 and have also suggested that the government is overcharging their clients. In court hearings, defense attorneys have also said the group had no real, cohesive plan to attack the Capitol that day.
The trial against the Proud Boys is scheduled to start on Monday with jury selection in DC federal court. All five defendants have pleaded not guilty to the indictment and face a maximum sentence of 20 years in a federal prison.
Enrique Tarrio, 38, is the longtime chairman of the Proud Boys.
Ethan Nordean, 31, is a Proud Boys leader from Washington state. Nordean, who goes by the moniker "Rufio Panman" after a member of Peter Pan's Lost Boys, rose to prominence in 2017 after a video of him knocking out an anti-fascist protester in one punch went viral.
Joseph Biggs, 38, is an Army veteran and Proud Boys leader from Florida. Biggs previously worked as a correspondent for Infowars, a far-right outlet that peddles false conspiracy theories.
Zachary Rehl, 36, is a former Marine and the president of his local Philadelphia chapter of the Proud Boys.
Dominic Pezzola, 44, is a Proud Boy from New York who goes by the nicknames "Spaz," "Spazzo," and "Spazzolini." Pezzola is a former Marine.
According to the indictment, leaders of the Proud Boys began planning for a "war" in the immediate aftermath of the 2020 presidential election.
"If Biden steals this election, [the Proud Boys] will be political prisoners. We won't go quietly...I promise," Tarrio allegedly posted online in the days after the election was called for Joe Biden.
By December, members of Proud Boys had started attending Washington, DC, rallies en masse. Some of the protests broke out in violence and the Proud Boys, who are known for street fighting, were in the middle.
When Trump announced the January 6 rally on Twitter, Tarrio and others decided to create a new national chapter of the Proud Boys for the event called the Ministry of Self Defense (MOSD) according to court documents. The MOSD was allegedly made up of more than 90 "hand selected members" and "rally boys" -- members who were willing to break the law -- and were encouraged not to wear the traditional Proud Boys uniform of black and yellow polos when they came to DC.
The MOSD, Tarrio allegedly informed new members, would have a "top down structure." He, Biggs and Nordean were viewed as the MOSD leaders, prosecutors say. Several others including Rehl were also part of MOSD leadership.
Tarrio was arrested in Washington, DC, on January 4, 2021, for burning a DC church's Black Lives Matter banner in December and bringing high-capacity rifle magazines into the district. He was ordered by a judge to leave the city. In encrypted leadership chats, Tarrio allegedly told other members he hoped his arrest could inspire people to lash out violently against police.
A group of approximately 100 Proud Boys met at the Washington Monument the morning of January 6, prosecutors say. Several of the members, including Biggs and Rehl, allegedly had walkie-talkie style radios, and Nordean and Biggs both used a bullhorn to direct the group as they marched to the Capitol.
The group arrived at the Capitol around 15 minutes before Congress was set to start the joint proceeding to certify the 2020 election, according to videos from that day, and walked to an access point on the west side of the building. A Proud Boy named Ryan Samsel was the first to charge and breach barricades on the Capitol grounds, prosecutors say, and he spoke to Biggs just one minute before acting.
As the battle at the Capitol ensued, members of the hand selected MOSD including Pezzola can be seen in videos consistently on the front lines of the riot, prosecutors say. Nordean, Biggs and Rehl allegedly stayed back, opting to follow once others had already broken through police lines.
When the mob arrived at the Capitol doors, Pezzola used a stolen police riot shield to smash a window, prosecutors say. The first members of the mob to breach the Capitol building, allegedly including Pezzola and Biggs, entered through that window. The Senate suspended its session minutes later.
Tarrio watched the chaos unfold from Baltimore, allegedly posting publicly on social media "Don't f***ing leave" and "Make no mistake...We did this..."
The Justice Department has already successfully prosecuted a seditious conspiracy case against leaders of the Oath Keepers, which could act as a model for prosecutors as they turn to the Proud Boys.
Both Oath Keepers founder Stewart Rhodes and Tarrio did not enter the Capitol during the hours-long breach, but during his trial, prosecutors successfully argued that Rhodes acted like a general overseeing his troops on January 6, a narrative prosecutors will likely employ against Tarrio.
Unlike the Oath Keepers, the Proud Boys have a long history of violent action -- a history that prosecutors will likely use to convince a jury that the group has a propensity toward violence and that the riot at the Capitol was not out of character.
In previous court filings, prosecutors have said that Tarrio, Biggs, Nordean, Rehl and other Proud Boys leaders encouraged their followers to "turn your brains off a little bit," and used those followers as "tools" to achieve their larger plan to interfere with the joint congressional proceeding.
If the Justice Department secures convictions for Tarrio and other Proud Boys leaders, the group will continue to exist, Rachel Carroll Rivas, a senior research analyst at the Southern Poverty Law Center who studies extremism told CNN.
"It's not hierarchical like a lot of militia movements," Rivas told CNN, noting the group doesn't depend on any one leader to act and gain power.
The group's goal, Rivas said, is focused on "creating chaos, creating fear through a sense of uncertainty and a lack of feeling of safety," which she says is meant to lead fewer people speaking up against the group.