Special counsel John Durham — the prosecutor examining the origins of the FBI’s investigation into a possible conspiracy between Russia and Donald Trump’s 2016 presidential campaign — has used a grand jury in recent months to seek documents and witness testimony, according to people familiar with the matter.

The burst of activity signals Durham’s inquiry, now more than two years old, remains active and is examining possible crimes — though it is unclear whether it has uncovered evidence that will ultimately support more charges. Durham’s recent inquiries, those familiar with the matter said, appear to focus on whether people outside of government might have given the FBI fabricated or exaggerated evidence to spur investigations, which could be a crime.

The people familiar with the matter spoke on the condition of anonymity to discuss an ongoing investigation. The interest in people outside of government was previously reported by the Wall Street Journal.

Durham’s investigation has long faced criticism, as Democrats and legal observers have worried that the prosecutor specially appointed by then-Attorney General William P. Barr was essentially out to undercut an investigation that dogged Trump’s campaign and much of his presidency. As Durham’s probe has continued into the Biden administration, some witnesses have privately grumbled that Attorney General Merrick Garland should push the special counsel to conclude his work. The Russia investigation, they argue, already has been scrutinized by Congress and the Justice Department inspector general, who found serious flaws but determined that it was opened with adequate basis.

Others argue that even if Durham’s inquiry is misguided, Garland should let it run its course without interference.

“It has struck me from the start as a fool’s errand at best, and a political task at worst, but to shut it down would give the appearance of political interference that would be unwise,” said former U.S. attorney Barbara McQuade.

A Justice Department spokesman assigned to handle inquiries about the Durham probe declined to comment.

Durham’s investigators have in the past asked witnesses about a wide range of topics, including the opening of the Russia investigation and the FBI’s efforts to obtain secret court orders to surveil Carter Page, a former adviser to Trump’s campaign in 2016.

He has examined in particular the FBI’s reliance on information provided by former British intelligence officer Christopher Steele as it obtained those orders, and Steele’s use of a source, Igor Danchenko, an analyst once affiliated with the Brookings Institution and who the Justice Department inspector general found was the subject of an FBI counterintelligence investigation from 2009 to 2011 that assessed his “documented contacts with suspected Russian intelligence officers.”

Steele had been hired to look into Trump by an opposition research group working for the law firm representing Hillary Clinton’s 2016 campaign and the Democratic National Committee.

Durham’s most recent inquiries, people familiar with the matter say, have focused in part on the authenticity of data given to the FBI about alleged cyber links between the former president’s company and Alfa Bank of Russia — a theory pushed to journalists by some computer scientists in the fall of 2016 on the basis of purported server connections they had discovered. The theory — which generated public pushback after it was published by Slate — essentially posited that Domain Name System lookups from Alfa Bank servers to a server with a Trump Organization-linked domain could signal a secret communications channel.

One of the researchers told the New Yorker in a story published in 2018 that his lawyer passed along the data to the FBI. Michael Sussmann, a Perkins Coie lawyer whose firm represented the DNC and the Clinton campaign, testified to the House Intelligence Committee in December 2017 that he talked with the FBI’s then general counsel, Jim Baker, in September 2016 about the information. Baker testified that he referred the matter to investigators.

Lawyers for Baker and Sussmann declined to comment.

According to a Justice Department inspector general report released publicly in December 2019, the bureau investigated the matter but “had concluded by early February 2017 that there were no such links” between the bank and the Trump Organization.

Durham, according to people familiar with the matter, appears to be examining the theory that presenting the information to the FBI could amount to making a false report to law enforcement. Alfa Bank has alleged in a Florida lawsuit that someone committed cyberattacks to generate digital records appearing to show secret communications between the bank and the Trump Organization. It is unclear whether Durham has uncovered any evidence to support that claim.

Durham’s interest in Alfa Bank-related matters is not wholly new. The New Yorker reported in October 2020 that computer scientists and others had been summoned to testify before a Durham-impaneled grand jury.

In July 2020, The Washington Post learned that investigators sought the cooperation of Indiana University informatics professor L. Jean Camp, and signaled their willingness to use a grand jury subpoena to obtain information related to her analysis of communications between the Trump Organization and Alfa Bank, a person familiar with the matter said. The school, though, resisted the matter — hiring a private lawyer for Camp — and, ultimately, Durham did not interview her, this person said.

“We were concerned these inquiries from the Justice Department might chill academic freedom,” Indiana University’s general counsel, Jackie Simmons, said in an interview with The Post last year.

So far, Durham has brought one criminal case. Kevin Clinesmith, a former FBI lawyer, pleaded guilty to doctoring an email that other officials relied on to justify secret surveillance of Page and was sentenced to probation.

In addition to any other cases he may bring, Durham also is expected to issue a public report when he is finished. Barr directed as much late last year in his order appointing Durham as a special counsel, writing that the prosecutor “shall submit to the Attorney General a final report, and such interim reports as he deems appropriate, in a form that will permit public dissemination.”

Ellen Nakashima contributed to this report.