Micah Coomer, circled at right, Joshua Abate, left in circle and Dodge Dale Hellonen, center in circle, in a still frame from surveillance camera footage, inside the Capitol building on Jan. 6, 2021. (from Criminal Complaint filed with the U.S. District Court for the District of Columbia)

Two Marines who worked in intelligence gathering and were on active duty during the Jan. 6 riot pleaded guilty Monday to their involvement with the mob at the U.S. Capitol, joining a colleague who admitted his participation last month.

Sgts. Joshua Abate, 22, and Dodge Dale Hellonen, 23, were arrested in January along with Cpl. Micah R. Coomer, 24. All three pleaded to the misdemeanor charge of illegally demonstrating inside the Capitol building.

While court documents don’t indicate when the three Marines were identified by law enforcement as members of the mob that sought to keep lawmakers from certifying President Biden’s 2020 election victory over Donald Trump, Hellonen admitted his involvement a year ago and Coomer’s Facebook account was searched in August 2021.

At the time of his plea, a Marines spokesman said Coomer was working as an engineer in the 1st Radio Battalion at Camp Pendleton, which handles intelligence drawn from electronic and telecommunication networks. Abate was working for the Marine Corps’ Cryptologic Support Battalion, which partners with the National Security Agency at Fort Meade. Hellonen was assigned to the Marine Raider Support Battalion, which supports special operations at Camp Lejune. The Intercept previously reported that all three men were given new intelligence-related assignments after Jan. 6.

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An attorney for Hellonen said in court Monday that her client will “likely” face consequences in the military system as well, but “it has not happened yet.” She added that “he may be separated” from the Marines rather than charged in military court.

As of May 19, the three Marines were still on active duty, said Yvonne Carlock, a service spokeswoman. It was not clear on Monday if any of them recently has been removed from the service.

The three men traveled to Washington, D.C. from Marine Corps Base Quantico in Prince William County, Va., according to the court record. They entered the Capitol about 10 minutes after other rioters first breached the building, and stayed inside for almost an hour. They joined chants of “Stop the Steal!” and “Four More Years!”; they put Coomer’s “Make America Great Again” hat on a statue in the Rotunda and took pictures of it.

They were identified to the FBI by fellow Marines; Abate also admitted his involvement in a security clearance interview in June 2022, more than a year after the riot. In that interview, Abate said the three “buddies” entered the Capitol together and “walked around and tried not to get hit with tear gas.” He said one of his friends also smoked a cigarette inside the Rotunda.

On Coomer’s Facebook account, investigators found discussion of “civil war” and “the boogaloo,” a reference to a far-right extremist movement that gained popularity in 2020.

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A fourth active-duty Marine, Maj. Christopher Warnagiris, was arrested in May 2021 and is set to go to trial this fall on charges that include felony obstruction of Congress and interfering with police. An active-duty Navy sailor who was stationed on an aircraft carrier in Norfolk at the time of the riot was arrested in April and charged with misdemeanor crimes. And a veteran re-enlisted in the Army after the FBI identified him as having attacked police outside the Capitol with chemical spray. He has been sentenced to 44 months in prison.

Over 10 percent of those charged with breaking the law during the Capitol assault have a military background, according to studies by the University of Maryland and George Washington University. The Proud Boys and the Oath Keepers, whose leaders have been convicted of engaging in seditious conspiracy, both recruited heavily among veterans. After the Capitol attack, the Pentagon updated its personnel policies to prohibit endorsement or promotion of extremist views and the Defense Department began engaging in “continuous vetting” of employeerecords. But officials said they did not plan to proactively monitor social media for violations and that they could not do much about veterans who began embracing such beliefs.

Coomer will be sentenced in late August. Abate and Hellonen will be sentenced in September.

“This is difficult for everyone,” Judge Ana C. Reyes told Hellonen. “I wish that I was meeting you under different circumstances.”

Emily Guskin contributed to this report.