Updated 2/16/21, 8:41 a.m.

WASHINGTON — The Democratic chairman of the House Homeland Security committee accused Donald Trump in a federal lawsuit on Tuesday of inciting the deadly insurrection at the U.S. Capitol and of conspiring with his lawyer and extremist groups to try to prevent Congress from certifying the results of the presidential election he lost to Joe Biden.

The lawsuit from Mississippi's Rep. Bennie Thompson is part of an expected wave of litigation over the Jan. 6 riot and is believed to be the first filed by a member of Congress. It seeks unspecified punitive and compensatory damages.

The case also names as defendants the Republican former president's personal lawyer Rudy Giuliani and groups including the Proud Boys and the Oath Keepers, extremist organizations that had members charged by the Justice Department with taking part in the siege.

A Trump adviser, Jason Miller, said in a statement Tuesday that Trump did not organize the rally that preceded the riot and "did not incite or conspire to incite any violence at the Capitol on Jan. 6th." A lawyer for Giuliani did not immediately return an email seeking comment.

The suit, filed in federal court in Washington under a Reconstruction-era law known as the Ku Klux Klan Act, comes three days after Trump was acquitted in a Senate impeachment trial that centered on allegations that he incited the riot, in which five people died. That acquittal is likely to open the door to fresh legal scrutiny over Trump's actions before and during the siege. Additional suits could be brought by other members of Congress or by law enforcement officers injured while responding to the riot.

Even some Republicans who voted to acquit Trump on Saturday acknowledged that the more proper venue to deal with Trump was in the courts, especially now that he has left the White House and lost certain legal protections that shielded him as president.

The suit traces the drawn-out effort by Trump and Giuliani to cast doubt on the election results even though courts across the country, and state election officials, repeatedly rejected their baseless allegations of fraud. Despite evidence to the contrary, the suit says, the men portrayed the election as stolen while Trump "endorsed rather than discouraged" threats of violence from his angry supporters in the weeks leading up to the assault on the Capitol.

"The carefully orchestrated series of events that unfolded at the Save America rally and the storming of the Capitol was no accident or coincidence," the suit says. "It was the intended and foreseeable culmination of a carefully coordinated campaign to interfere with the legal process required to confirm the tally of votes cast in the Electoral College."

Presidents are historically afforded broad immunity from lawsuits for actions they take in their role as commander in chief. But the lawsuit filed Tuesday was brought against Trump in his personal, not official, capacity and alleges that none of the behavior at issue had to do with his responsibilities as president.

"Inciting a riot, or attempting to interfere with the congressional efforts to ratify the results of the election that are commended by the Constitution, could not conceivably be within the scope of ordinary responsibilities of the president," Joseph Sellers, a lawyer for Thompson, said in an interview.

"In this respect, because of his conduct, he is just like any other private citizen," he said.

Sellers, a lawyer with the Washington law firm of Cohen Milstein, filed the case along with the NAACP. Several other members of Congress are expected to join.

Though the impeachment case focused squarely on accusations of incitement, the lawsuit more broadly accuses Trump of conspiring to disrupt the constitutional activities of Congress — namely, the certification of election results establishing Biden as the rightful winner — through a monthslong effort to discredit the outcome and to lean on individual states and his own vice president to overturn the contest.

The case against Trump was brought under a provision of the Ku Klux Klan Act of 1871, which was passed in response to KKK violence and prohibits violence or intimidation meant to prevent Congress or other federal officials from carrying out their constitutional duties.

"Fortunately, this hasn't been used very much," Sellers said. "But what we see here is so unprecedented that it's really reminiscent of what gave rise to the enactment of this legislation right after the Civil War."

The suit cites incendiary comments that Trump and Giuliani made in the weeks leading up to the riot and on the day of it that lawyers say were designed to mobilize supporters to work to overturn the election results and to prevent the congressional certification process. That process was temporarily interrupted when Trump loyalists broke into the Capitol.

Trump told supporters at a rally preceding the riot to "fight like hell," but lawyers for the former president adamantly denied during the impeachment trial that he had incited the riot. They pointed to a remark during his speech in which he told the crowd to behave "peacefully" that day. Defense lawyers are likely to revisit those assertions in the lawsuit. They may also argue, as was done during the impeachment case, that Trump's speech was protected by the First Amendment.

Updated 1/15/21, 2:48 p.m.

PHOENIX — Federal prosecutors who initially said there was "strong evidence" the pro-Trump mob that stormed the U.S. Capitol last week aimed to "capture and assassinate elected officials" backed away from the allegation after the head of the investigation cautioned Friday that the probe is still in its early stages and there was no "direct evidence" of such intentions.

The accusation came in a court filing by prosecutors late Thursday in Phoenix in the case against Jacob Chansley, the Arizona man who took part in the insurrection while sporting face paint, no shirt and a furry hat with horns.

"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," a prosecutor wrote in a memo urging the judge to keep Chansley behind bars. But at a hearing for Chansley later in the day in Phoenix, another prosecutor, Todd Allison, struck the line from the memo.

Allison said the statement may very well end up being appropriate at Chansley's trial, but said prosecutors didn't want to mislead the court and don't have to rely on the stricken statement to argue that he should remain in jail. Ultimately, a judge on Friday ordered Chansley to be jailed until his trial.

Earlier on Friday, Michael Sherwin, acting U.S. attorney for the District of Columbia, backed away from the assassination claims, saying they have "no direct evidence at this point of kill, capture teams."

Sherwin said there appears to have been confusion among some prosecutors in part because of the complexity of the investigation and number of people involved. Prosecutors raised a similar prospect Thursday in the case of a former Air Force officer who they alleged carried plastic zip-tie handcuffs because he intended "to take hostages."

The sprawling investigation involves multiple cities and jurisdictions, in part because so many of the rioters simply went home; only 13 were arrested in the moments after the building was cleared.

The FBI has been investigating whether any of the rioters had plotted to kidnap members of Congress and hold them hostage, focusing particularly on the men seen carrying plastic zip-tie handcuffs and pepper spray.

Although the assassination claim from the court filing was stricken by prosecutors, prosecutors didn't back away from the statement that Chansley, when climbing up to the dais where Vice President Mike Pence had been presiding moments earlier, wrote a threatening note to Pence that said: "It's only a matter of time, justice is coming."

Pence and congressional leaders had been ushered out of the chamber by the Secret Service and U.S. Capitol Police shortly before the rioters stormed into the room.

Chansley's attorney, Gerald Williams, said he hasn't seen any images of his client engaging in dangerous conduct while in the Capitol. "He was merely there acting as a protester," Williams said, pointing out that his client has no prior criminal history and agreed to talk to investigators.

Allison said Chansley was proud of his actions on the day of the insurrection and wanted to go to Washington for Biden's inauguration on Wednesday. Allison described Chansley as someone who believes in conspiracy theories and "is not connected to reality."

U.S. Magistrate Judge Deborah Fine, in ordering Chansley jailed until trial, concluded he is at risk of fleeing and obstructing justice in his case and poses a danger to the community. Echoing the words of prosecutors, Fine said it was appropriate to say Chansley was an active participant in a violent insurrection that attempted to overthrow the government.

Fine said Chansley went through barricades, was among the first people to force their way into the Capitol building, disobeyed orders by an officer to leave, refused the officer's request to use Chansley's bullhorn to tell rioters to leave the Senate chamber and wrote the note to the vice president.

"Mr. Chansley's idea of protesting is committing the unlawful acts that we are discussing here," Fine said.

Chansley, who calls himself the "QAnon Shaman" and has long been a fixture at Trump rallies, was arrested Saturday at the FBI field office in Phoenix.

News photos show him at the riot shirtless, with his face painted and wearing a fur hat with horns, carrying a U.S. flag attached to a wooden pole topped with a spear.

QAnon is an apocalyptic and convoluted conspiracy theory spread largely through the internet and promoted by some right-wing extremists.

Chansley told investigators he came to the Capitol "at the request of the president that all 'patriots' come to D.C. on January 6, 2021." An indictment unsealed Tuesday in Washington charges him with civil disorder, obstruction of an official proceeding, disorderly conduct in a restricted building, and demonstrating in a Capitol building. He hasn't entered a plea to the charges.

More than 80 people are facing charges stemming from the violence, including more than 40 people in federal court. Dozens more were arrested for violating a curfew that night.

The federal charges brought so far are primarily for crimes such as illegal entry, but prosecutors have said they are weighing more serious charges against at least some of the rioters. Some were highly-trained ex-military and police.

Sherwin said this week that he has organized a group of national security and public corruption prosecutors whose sole focus is to bring sedition charges for the "most heinous acts that occurred in the Capitol."

The Air Force officer, Col. Larry Rendall Brock, Jr., was arrested Sunday in Texas after being photographed on the Senate floor during the deadly riot wearing a helmet and heavy vest and carrying plastic zip-tie handcuffs.

"He means to kidnap, restrain, perhaps try, perhaps execute members of the U.S. government," Assistant U.S. Attorney Jay Weimer said, without providing specifics.

Brock's attorney, Brook Antonio II, noted that he has only been charged with misdemeanors. Antonio said there was no direct evidence of Brock breaking doors or windows to get into the Capitol, or doing anything violent once he was inside.

On Thursday, authorities also arrested a man from Utah who filmed the fatal shooting of the Trump supporter inside the Capitol. Police shot Ashli Babbitt, an Air Force veteran, as she was trying to climb through a broken window into the speaker's lobby.

John Sullivan, 26, a self-described journalist who filmed the shooting, told the AP earlier this week that he was only there to document the events at the U.S. Capitol and didn't attend the riot as a Trump supporter.

In one video, Sullivan can be heard cheering on the rioters as they broke through the final barricade before the Capitol and saying, "We did this together. ... We are all a part of history."