Top leaders in the Oath Keepers militia group indicted on seditious conspiracy charges over the Capitol attack had contacts with the Proud Boys and a figure in the Stop the Steal movement and may also have been in touch with the Republican congressman Ronny Jackson, newly released text messages show.

The texts – which indicate the apparent ease with which Oath Keepers messaged Proud Boys – could strengthen a theory being explored by the House January 6 committee and the US justice department: that the Capitol attack included a coordinated assault.

Oath Keepers text messages released in a court filing on Monday night showed members of the group were in direct communication with the Proud Boys leader Enqrique Tarrio in the days before the Capitol attack.

In an exchange on 4 January 2021, the Oath Keepers Florida chapter leader, Kelly Meggs, indicates an attempt to call Tarrio after learning of his arrest.

“I just called him no answer,” Meggs texted a group chat. “But he will [call if] he’s out.”

That close relationship is certain to be of interest to the House committee as it zeroes in on whether the Oath Keepers and the Proud Boys coordinated an attack on the Capitol in an attempt to stop certification of Joe Biden’s election win over Donald Trump.

As the Guardian first reported, the committee has amassed deep evidence of connections between the far-right groups which could play a role in establishing whether Trump oversaw a criminal conspiracy as part of his attempt to hold on to power.

The newly released text messages also show a new link between the Oath Keepers and an unnamed figure from the Stop the Steal movement, which has ties to the pro-Trump operative Roger Stone and to Ali Alexander, a prominent Trump ally and activist.

On the evening of 1 January, Stewart Rhodes, the national leader of the Oath Keepers, texted to say he was adding an unidentified person affiliated with Stop the Steal to the group chat, to help them prepare for January 6.

The name was redacted in the released texts but Rhodes described an “event producer for Stop the Steal. He requested I add him here. He can sort out who is doing what in the creative chaos that will be Jan 5/6.

“He’s a good egg.”

It was not clear whether Rhodes misattributed an affiliation to Stop the Steal, given the January 6 rally at the Ellipse was a Save America event. Neither Alexander nor Stone appeared to message the group chat or were otherwise involved.

New Republican connection

The Oath Keepers text messages also show a connection to Ronny Jackson that allowed one of its members to learn that the Texas congressman – Trump’s former White House doctor – needed protection as the Capitol attack unfolded.

The potential connection between the Oath Keepers and a Republican member of Congress could mark a new investigatory direction for the committee and the justice department: whether Jackson or others might have had advance knowledge of the Oath Keepers’ plans.

In the exchange on January 6, an unidentified Oath Keeper texts the group chat that “Ronnie Jackson (TX) office inside Capitol – he needs OK help. Anyone inside?”

The same Oath Keeper provides an update less than 10 minutes later: “Dr Ronnie Jackson – on the move. Needs protection. If anyone inside cover him. He has critical data to protect.”

Rhodes quickly responds: “Give him my cell.”

In a statement to the Guardian, a spokesperson said Jackson “is frequently talked about by people he does not know. He does not know nor has he ever spoken to the people in question”.

Asked if Jackson was never in contact with the Oath Keepers, the spokesperson did not answer.

The House committee has not given any indication that Republican members of Congress were connected to a potential conspiracy overseen by Trump that would connect his plan to have then-vice president Mike Pence overturn the election with the Capitol attack.

The Oath Keepers texts were included in a motion for release from pre-trial detention by Ed Vallejo, one of 11 group members facing charges of seditious conspiracy. On January 6, prosecutors say, Vallejo was at a Comfort Inn in Virginia with a cache of weapons, meant to act as a quick reaction force.

The messages show the Oath Keepers discussed providing security for prominent Trump allies including Stone, Alexander, Alex Jones, Lin Wood and Mike Flynn, Trump’s former national security adviser.

One week before January 6, Rhodes, the leader of the Oath Keepers, mentioned requests to provide security for Bianca Garcia, president of the group Latinos for Trump, for which Tarrio, the Proud Boys leader, was also chief of staff.

The next day, Meggs, the Florida Oath Keepers leader who would ultimately lead Stone’s security detail, boasted that he had spoken to Stone the night before. Jessica Watkins, another member of the Oath Keepers, said she was also in touch with Stone.

“Roger Stone just asked for security,” Watkins texted the group chat on 1 January, to which Meggs responded: “Who reached out to you? I [spoke] to him Wednesday.”

Meggs – using the alias “OK Gator 1” – added: “I just texted him.”

Though the Oath Keepers discussed providing security for other Trump allies, the extent of their voluntary services remains unclear. Alexander said in a recent statement that the Oath Keepers did not perform security duties for him on January 6.