The acquittal of former President Donald J. Trump at his second impeachment trial will hardly be the last or decisive word on his level of culpability in the assault on the Capitol last month.

While the Justice Department officials examining the rash of crimes committed during the riot have signaled that they do not plan to make Mr. Trump a focus of the investigation, the volumes of evidence they are compiling may eventually give a clearer — and possibly more damning — picture of his role in the attack.

Case files in the investigation have offered signs that many of the rioters believed, as impeachment managers have said, that they were answering Mr. Trump’s call on Jan. 6. The inquiry has also offered evidence that some pro-Trump extremist groups, concerned about fraud in the election, may have conspired together to plan the insurrection.

“If this was a conspiracy, Trump was the leader,” said Jonathan Zucker, the lawyer for Dominic Pezzola, a member of the far-right Proud Boys group who has been charged with obstructing police officers guarding the Capitol. “He was the one calling the shots.”

As the sprawling investigation goes on — quite likely for months or even years — and newly unearthed evidence brings continual reminders of the riot, Mr. Trump may suffer further harm to his battered reputation, complicating any post-presidential ventures. Already, about a dozen suspects have explicitly blamed him for their part in the rampage — a number that will most likely rise as more arrests are made and legal strategies develop.

Some defendants, court papers show, said they went to Washington because Mr. Trump encouraged them to do so, while others said they stormed the Capitol largely because of Mr. Trump’s appeal to “fight like hell” to overturn the election. One man — charged with assaulting the police — accused the former president of being his accomplice: In recent court papers, he described Mr. Trump as “a de facto unindicted co-conspirator” in his case.

This week, prosecutors said that Jessica M. Watkins, a member of the Oath Keepers militia group, had been “awaiting direction” from Mr. Trump about how to handle the results of the election, only days after votes were cast. In court papers, the prosecutors quoted a text message the defendant, Ms. Watkins, sent to an associate on Nov. 9, saying that Mr. Trump had “the right to activate units.”

“If Trump asks me to come,” Ms. Watkins cryptically wrote, “I will.”

Legal scholars have questioned the viability of faulting Mr. Trump in cases connected to the Capitol attack, noting that defendants would have to prove not only that they believed he authorized their actions, but also that such a belief was reasonable.

But even if trying to offload responsibility onto Mr. Trump may prove ineffective at a trial, legal experts have acknowledged it might ultimately help mitigate the punishment for some people convicted of a crime at the Capitol.

More than 200 people altogether have been charged with federal crimes in the attack, most on relatively minor counts like disorderly conduct and unlawful entry. The one place where Mr. Trump might face charges connected to the election is Fulton County, Ga., where the local district attorney has announced an investigation into whether he interfered with state officials in charge of counting votes.

The “Trump made me do it” defense made a cameo appearance in a remarkable split-screen moment on Wednesday: As House impeachment managers were describing Mr. Pezzola’s role in the Capitol attack (noting that he had used a plastic riot shield to smash a window at the building), at the exact same time, Mr. Pezzola himself was in court asking a judge to release him pending trial — in part because he had been following Mr. Trump’s orders.

Mr. Pezzola, a former Marine, did not consider himself a violent criminal, but instead a “patriot” who responded to “the entreaties of the-then commander in chief, President Trump,” his lawyer, Mr. Zucker, had written in a court filing that morning. When Mr. Trump made baseless claims that the election had been stolen, Mr. Pezzola felt a duty to help, Mr. Zucker wrote, adding that his client thus became “one of millions of Americans who were misled by the president’s deceptions.”

Mr. Trump’s impeachment lawyers argued in the Senate this week that his fiery speech before the riot was protected by the First Amendment, and was not an incitement to violence. And while Mr. Pezzola’s claims that he was acting “out of conscience” in storming the Capitol may be true, they are also — for a man facing serious time in prison — slightly self-serving.

Still, other rioters charged in the Capitol attack have made similar claims in trying to stay out of jail, arguing, for example, that they cannot be considered a danger to the community given that Mr. Trump is out of office and thus, they say, unable to incite them further.

A lawyer for Jorge Riley, who shared dozens of Facebook posts as he stormed into the Capitol, said at a hearing last month that his client had flown from his home in Sacramento, Calif., to join the mob in Washington — or, as he put it, people who were “called to a rally by the president of the United States.”

Prosecutors have accused Mr. Riley, a former leader of the California Republican Assembly, a political activist group, of trying to find and harass Speaker Nancy Pelosi.

“The person for whom it was done — the person who egged it on and encouraged it — is no longer in power and does not have a voice, so that is not likely to recur,” his lawyer, Timothy Zindel, said of Mr. Trump in court.

In a separate case, a lawyer for Patrick McCaughey, accused of assaulting two police officers, wrote in a court filing this month that Mr. Trump was “somewhat of a de facto unindicted co-conspirator.”

Mr. McCaughey, whose story was featured at the impeachment trial this week, pushed his way to the front of a mob fighting to break through police lines at the Capitol and pinned one officer against a door, nearly choking him, prosecutors have said.

But his lawyer, Lindy R. Urso, argued in a court filing that Mr. McCaughey would, like others in the crowd, have protested peacefully had Mr. Trump not incited them to violence.

The efforts to blame Mr. Trump are, of course, a calculated legal defense and may not work to exonerate them of crimes committed at the Capitol, even if they were inspired by Mr. Trump’s words.

Ethan Nordean, a leader of the Proud Boys in Seattle, was “egged on” by Mr. Trump into believing the election was stolen, his lawyer wrote in a court filing this month. But prosecutors have said that Mr. Nordean’s online posts suggest that he and other Proud Boys were planning before Jan. 6 to breach police barricades at the Capitol.

On Dec. 27, for instance, Mr. Nordean posted on the social media site Parler asking for donations to buy protective gear and communications equipment, according to a criminal complaint. Shortly before the riot, prosecutors said, he also spoke on a podcast about the Proud Boys’ plan to appear in Washington in disguise, not in their typical black-and-yellow colors.

In a similar fashion, prosecutors have said there is evidence that Ms. Watkins and two other Oath Keepers charged with her, Thomas E. Caldwell and Donovan Crowl, premeditated the attack.

Mr. Caldwell, 66, a former Navy officer, advised his fellow militia members to stay at a particular Comfort Inn in the Washington suburbs, noting that it offered a good base to “hunt at night” — an apparent reference to chasing left-wing activists. Ms. Watkins, 38, set up a communications system for use in the assault on the chatting app Zello, prosecutors said.

In text messages obtained by the F.B.I., the three Oath Keepers appear to anticipate — even welcome — conflict in the postelection period. In one message, from Nov. 16, Mr. Crowl tells Mr. Caldwell, “War is on the horizon.” In another, just days later, Mr. Caldwell tells Ms. Watkins that he is “worried about the future of our country.” Then, court papers say, he adds, “I believe we will have to get violent to stop this.”

On Dec. 29, Ms. Watkins wrote to Mr. Crowl about the Jan. 6 event in Washington.

“Trump wants all able bodied Patriots to come,” she said, adding, “If Trump activates the Insurrection Act, I’d hate to miss it.”

As for Mr. Pezzola, his lawyer said he felt betrayed.

“He went to Washington because Trump asked him to save the country,” Mr. Zucker said. “Then he got arrested and Trump went to play golf.”

Adam Goldman contributed reporting.