WASHINGTON – The Justice Department is investigating communications between right-wing extremists who violated the Capitol and Roger J. Stone Jr., a close associate of former President Donald J. Trump, to see if Mr. Stone played a role in the extremists’ plans To disrupt the confirmation of President Biden’s election victory, a person familiar with the matter said on Saturday.

Should investigators find any news that Mr. Stone knew about or was participating in these plans, they would have a factual basis to launch a full criminal investigation into him, according to the person who spoke on condition of anonymity to discuss continued investigation. While this is far from certain, prosecutors at the U.S. law firm in Washington will likely if they find this connection.

Mr. Stone, a self-described fixer for Mr. Trump, escaped a 40-month sentence when the former president commuted his sentence in July and pardoned him in late December. Mr Stone had been convicted of seven offenses, including obstructing a House of Representatives investigation into possible links between the Trump campaign and Russia’s efforts to meddle in the 2016 election, lie to Congress and manipulate witnesses. However, this pardon does not protect Mr. Stone from future law enforcement actions.

Justice Department officials have been debating for weeks whether to open a full investigation into Mr. Stone, the person said. While Mr. Stone was speaking at an arson rally the day before the attack, right-wing extremists serving as his bodyguards and standing outside the Capitol, these actions are not crimes themselves.

But the FBI also has videos and other information suggesting that in the days leading up to and including the day of the attack, Mr. Stone was linked to men who eventually stormed the building and broke the law, those with the investigation said familiar person. This has given investigators a window in which to examine communications to see if Mr Stone knew of any plans to break through the complex.

The Washington Post previously reported that the Justice Department was investigating Mr Stone’s possible links with right-wing extremists at the Capitol.

The New York Times has identified at least six members of the Oath Keepers, a right-wing extremist group formed by former military and law enforcement officials who guarded Mr. Stone and were later seen in the Capitol after a pro-Trump mob violently builds the building. Prosecutors have accused two of these men of plotting to attack Congress.

A Justice Department spokesman declined to comment. Mr. Stone did not immediately respond to a request for comment.

In a statement posted online this month, Mr. Stone denied any role in the “lawless attack” and said that members of the Oath Guards “should be prosecuted” if there is evidence that they have broken the law. He added that he “saw no evidence of any illegal activity by members of the group”.

A day after the Capitol attack, Michael Sherwin, the US attorney in Washington, told reporters that he would not rule out bringing charges against Mr. Trump or his associates for their possible role in inciting or otherwise encouraging the mob.

“We look at all of the actors, not just the people who entered the building,” Sherwin said. When asked if such goals would include Mr. Trump, who admonished supporters during a rally near the White House on Jan. 6, telling them that they “could never retake our country with weakness,” Mr. Sherwin stood by his testimony . “We all look at actors,” he said. “If the evidence fits the elements of a crime, they will be charged.”

Another member of Mr. Sherwin’s office soon appeared to be tracing those remarks back to them, suggesting that individuals in Mr. Trump’s orbit were unlikely to be examined. But Mr. Sherwin later said he stood by his original statement.