An alleged militia leader was arrested Tuesday for being involved in the "planning and coordinating" of the Jan. 6 storming of the Capitol, as the FBI’s hones its efforts on extremist groups suspected of being linked to the attack, court papers show.

Thomas Edward Caldwell is one of the multiple alleged militia members to be connected, so far, with the Capitol Hill insurrection. Federal investigators described the 65-year-old Virginia man as having a "leadership role" within a paramilitary group known as the Oath Keepers, according to an affidavit for Caldwell’s arrest.

"We need to do this at the local level"

— Thomas Edward Caldwell, in a Facebook message following Jan. 6 insurrection (criminal complaint) 

Oath Keepers ‒ identified in court papers as a "loosely organized collection of militia who believe that the federal government has been coopted (s.i.c.) by a shadowy conspiracy that is trying to strip American citizens of their rights" ‒ were seen in photographs on Capitol grounds on Jan. 6.

Investigators scoured Caldwell’s Facebook page and found that Caldwell "was involved in planning and coordinating the January 6 breach," the affidavit states. Caldwell allegedly made arrangements for other Oath Keepers to stay in a Virginia hotel, reportedly writing on Facebook: "This is a good location and would allow us to hunt at night if we wanted to."

He references another alleged Oath Keepers leader’s potential "call to arms," and adds: "This is one we are doing on our own," according to the affidavit.

Screenshot of video taken by Thomas Caldwell.

Screenshot of video taken by Thomas Caldwell. (Criminal complaint)

Just hours after the insurrection, Caldwell purportedly wrote in a Facebook message: "Us storming the castle. Please share ... I am such an instigator!"

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"Proud boys scuffled with cops and drove them inside to hide. Breached the doors. One guy made it all the way to the house floor, another to Pelosi’s office," he wrote in a different missive. "A good time."

But his messages didn’t stop there, according to authorities.

"We need to do this at the local level," he allegedly wrote in a second message less than a minute later. "We need to do this at the local level. Lets (s.i.c) storm the capitol in Ohio. Tell me when!"

Sources told Fox News he was charged with conspiracy to commit an offense against the U.S. government. Court papers show he was also charged with obstruction of an official proceeding; knowingly entering or remaining in any restricted building or grounds without lawful authority; and violent entry or disorderly conduct.

Caldwell is believed to be the first rioter hit with conspiracy charges. He could not be reached despite several attempts by Fox News. 

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Among the hundreds who stormed the Capitol on Jan. 6 were eight to 10 people wearing "paramilitary equipment" and clothing that identified them as members of the Oath Keepers, authorities said. They moved "in an organized and practiced fashion and force[d] their way to the front of the crowd gathered around a door to the U.S. Capitol," court papers state.

Two of those members allegedly include Jessica Watkins and Donovan Crowl.

Watkins and Crowl, both from Ohio, are being held at a county jail in Dayton, after being arrested Monday. Federal documents identify them as members of the Ohio State Regular Militia, dues-paying members of the Oath Keepers.

Watkins, a 38-year-old self-described commanding officer of the Ohio State Regular Militia, posted video and comments on Jan. 6 on the Parler social media site, investigators said.

In one instance, she posted a picture of herself and included the caption, "Me before forcing entry into the Capitol Building."

Photo of social media post by Jessica Watkins.

Photo of social media post by Jessica Watkins. (Criminal complaint.)

Watkins also reportedly posted that entry was forced through the back door of the Capitol.

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Crowl was identified in a New Yorker magazine article titled, "A Former Marine Stormed the Capitol as Part of a Far-Right Militia." He and Watkins were charged with entering a restricted building or grounds; violent entry or disorderly conduct, and obstruction of an official proceeding.

They are among more than 125 people arrested so far on charges related to the Jan. 6 violent insurrection, which led to the deaths of a Capitol police officer and four others.

Fox News’ David Spunt and The Associated Press contributed to this report.