Prosecutors in the United States now believe supporters of President Donald Trump planned to "capture and assassinate elected officials" in their siege of the Capitol building last week, according to a new court filing.
The filing, submitted by Justice Department lawyers late Thursday, sought the detention of Jacob Chansley of Arizona, the QAnon conspiracy theorist pictured in the riot dressed as a horned shaman at the desk of Vice-President Mike Pence.
"Strong evidence, including Chansley's own words and actions at the Capitol, supports that the intent of the Capitol rioters was to capture and assassinate elected officials in the United States government," prosecutors said of the January 6 siege.
They said Chansley, 33, left a note for Pence at the dais in the Senate Chamber where the second-in-command had been standing just minutes before, which read: "It's only a matter of time, justice is coming."
The filing gives further insight into the FBI probe on the day of chaos at the centre of US democracy, which left elected officials holed up fearing for their lives and at least five people dead, including one police officer.
It comes as authorities lay charges against individuals involved in the riot, including a man who flew the confederate flag inside the building, a man who wore a "Camp Auschwitz" sweatshirt and a US Olympic swimming gold medalist.
Chansley was due to appear in court on Friday at press time. Prosecutors said he is a regular drug user and likely has mental health problems.
"Chansley has spoken openly about his belief that he is an alien, a higher being, and he is here on Earth to ascend to another reality," the filing read.
Prosecutors requested he be detained as he "poses serious risks of flight and danger to the community."
Chansley subscribes to QAnon, the far-right conspiracy theory blamed for fuelling a section of Trump's supporters at the Capitol building.
Social media platforms have started cracking down on its followers, who believe Trump is waging a secret war on a liberal cult of Satan-worshipping paedophiles.
US House Speaker Nancy Pelosi said Friday that retired general Russel Honore, who coordinated the Hurricane Katrina response, will oversee an immediate security review at the US Capitol following last week's deadly riot, in which five people lost their lives.
In a bipartisan vote, Trump was impeached Wednesday for "incitement of insurrection" by egging on a huge crowd of his supporters to march on Congress.
But Pelosi on Friday declined to reveal when she will send the article of impeachment over to the Senate, a process that would trigger a trial of the president.
"You'll be the first to know when we announce that we're going over there," she told reporters.
"We must subject this whole complex to scrutiny in light of what happened, and the fact that the inauguration is coming," the top Democrat told reporters, referring to Biden's upcoming swearing-in on the steps of the very Capitol where rioters fought with police and plotted to kill lawmakers.
A handful of conservative House Republicans loyal to Trump are also facing scrutiny for their role in potentially coordinating with hardline activists who helped plan the action on the Capitol.
"If in fact it is found that members of Congress were accomplices to this insurrection, if they aided and abetted the crime," Pelosi said, "there may have to be actions taken beyond the Congress in terms of prosecution."
The centre of Washington was in lockdown early Friday as more than 20,000 armed National Guard troops were mobilised after officials warned of the threat of more violence at the presidential inauguration of Joe Biden on January 20, as well as in state capitals.
The National Mall in downtown Washington, which is normally packed with people every four years for presidential inaugurations, will also be closed at the request of the Secret Service because of security concerns.
In a sign that the stuttering presidential transition may be picking up speed, US media reported Friday that Pence held a telephone conversation with his successor Kamala Harris.
No more verified details were immediately available about the call, which took place on Thursday, but The New York Times said the vice-president offered his congratulations and belated assistance to Harris. It was the first time the pair had spoken since they debated one another during the campaign.
Trump still has not reached out to Biden and has only obliquely referred to his rival's victory by promising a smooth transition. The president has said he will not attend Biden's inauguration. Pence has said he will.
An official confirmed to AFP on Friday that Trump will fly out of Washington early on Wednesday, before the inauguration begins. He will go to his Mar-a-Lago club in Florida, where he plans to stay.