Some Democratic lawmakers have suggested that Trump and others should potentially face criminal charges for allegedly encouraging the fatal riot, but on Friday the Justice Department official told reporters that federal investigators are not pursuing such matters.
"We don't expect any charges of that nature," Ken Kohl, a senior prosecutor in the U.S. attorney's office in Washington, said.
Federal authorities have already filed charges against more than a dozen protesters who infiltrated the U.S. Capitol on Wednesday, and officials are working with the Metropolitan Police Department in Washington to investigate the death of officer Brian Sicknick as a result of the melee.
Overnight, in the wake of Sicknick's death, Rep. Rosa Delauro, D-Conn., issued a statement saying that while "the mob who attacked the People's House" must be charged, "those who instigated them" must also be held accountable.
Rep. Don Beyer, D-Va., issued a similar statement, saying that "those who brought about this awful crime must be prosecuted and brought to justice."
Speaking to an agitated crowd just before many in the crowd began marching to the U.S. Capitol on Wednesday, the president and several of his closest allies reiterated baseless claims that the White House was being fraudulently stolen from Trump.
"We're just not going to let" Joe Biden become president, Trump declared. "We're going to have to fight much harder. … We're going to walk down to the Capitol, and … you have to show strength, and you have to be strong."
Trump's son Donald Trump Jr. told the crowd, "If you just roll over, if you don't fight in the face of glaring irregularities and statistical impossibilities … if you're going to be the zero and not the hero, we are coming for you."
Trump's personal attorney Rudy Giuliani was even more blunt, insisting: "Let's have trial by combat."
On Thursday, the acting U.S. attorney in Washington, D.C., Michael Sherwin, declined to rule out charges against Trump and others for their incendiary rhetoric, but his colleague's official comments on Friday suggested that federal investigators would be focusing their efforts elsewhere.
Nevertheless, Justice Department spokesman Marc Raimondi said in a statement to ABC News that the investigation is "extremely complex and ongoing ... and we will continue to follow the facts and the law."
A current Justice Department official called it a "moonshot" to suggest that "there's any hook for criminal liability for Trump."
"Encouragement can cause criminal liability, but it's got to be … more than a politician making reckless comments to their base," especially because a politician's "blustery, incendiary comments" are often still protected by the First Amendment, the official said, speaking on the condition of anonymity because he was not authorized to speak publicly.
"[Even] if Trump were in communication with protesters who said, 'We're going to storm the Capitol,' and Trump said, 'Go for it,' I don't know if that gets you [to a criminal charge]," the official added.
Jordan Strauss, who served in the Justice Department's National Security Division during the Obama administration, agreed, telling ABC News, "It would be hard to bring a criminal prosecution."
According to federal law, people can face rebellion or insurrection charges for offering "aid or comfort" to rioters, so "a broad reading of the sedition and insurrection laws could theoretically allow for prosecution of senior officials" -- but "the legal issues will be thorny," said Strauss, now an executive at the global intelligence firm Kroll and its parent company, Duff & Phelps.
A former Justice Department prosecutor who specialized in national security cases and criminal conspiracies told ABC News that "at least in theory, anyone who incited [Wednesday's riots] could be charged as an aider and abettor" under seditious conspiracy laws, but such charges would likely be a stretch given what Trump did -- and did not -- say on national television.
"Is there evidence in the videos of an intent to incite violent action? Or is it just intent to encourage a lawful protest?" the former federal prosecutor said. "I think the conduct was deplorable. Sometimes that's the same as criminal, but not always. And probably not here."
"Charging a political figure with what can be argued is political speech is, in my view, sending us further down the road to a banana republic," the former federal prosecutor added.
ABC News' Allison Pecorin contributed to this report.