WASHINGTON (AP) — The prosecutor tasked with examining the U.S. government’s investigation into Russian election interference charged a prominent cybersecurity lawyer on Thursday with making a false statement to the FBI.

The case against the attorney, Michael Sussmann, is just the second prosecution brought by special counsel John Durham in two-and-a-half years of work. Yet neither case brought by Durham undoes the core finding of an earlier investigation by Robert Mueller that Russia had interfered in sweeping fashion on behalf of Donald Trump’s 2016 presidential campaign and that the Trump campaign welcomed that aid.

It lays bare the wide-ranging and evolving nature of Durham’s investigation. In addition to having scrutinized the activities of FBI and CIA officials during the early days of the Russia probe, it has also looked at the behavior of private individuals like Sussman who provided the U.S. government with information as it scrambled to determine whether Trump associates were coordinating with Russia to tip the election’s outcome.

The indictment accuses Sussmann of hiding that he was working with Hillary Clinton’s presidential campaign during a September 2016 conversation he had with the FBI’s general counsel, when he relayed concerns from cybersecurity researchers about potentially suspicious contacts between Russia-based Alfa Bank and a Trump organization server. The FBI looked into the matter but found no connections. Sussmann is a former federal prosecutor who specializes in cybersecurity.

Sussmann’s lawyers, Sean Berkowitz and Michael Bosworth, said their client is a highly-respected national security lawyer who had previously worked in the Justice Department under both Republican and Democratic administrations and said they were confident he would prevail at trial and “vindicate his good name.”

“Mr. Sussmann has committed no crime,” they said in a statement. “Any prosecution here would be baseless, unprecedented, and an unwarranted deviation from the apolitical and principled way in which the Department of Justice is supposed to do its work.”

The Alfa Bank matter was not a pivotal element of the Russia probe and was not even mentioned in Mueller’s 448-page report in 2019. Still, the indictment may give fodder to Russia investigation critics who regard it as politically tainted and engineered by Democrats.

Sussmann’s former firm, Perkins Coie, has deep Democratic connections. A then-partner at the firm, Marc Elias, brokered a deal with the Fusion GPS research firm to study Trump’s business ties to Russia. That work, by former British spy Christopher Steele, produced a dossier of research that helped form the basis of flawed surveillance applications targeting a former Trump campaign official, Carter Page.

A spokesman for Perkins Coie said Sussmann, “who has been on leave from the firm, offered his resignation from the firm in order to focus on his legal defense, and the firm accepted it.”

The Durham investigation has already spanned months longer than the earlier special counsel probe into Russian election interference conducted by Mueller, the former FBI director, and his team. The investigation was slowed by the coronavirus pandemic and experienced leadership tumult following the abrupt departure last fall of a top deputy on Durham’s team.

Though Trump had eagerly anticipated Durham’s findings in hopes that they’d be a boon to his reelection campaign, any political impact the conclusion may have once had has been dimmed by the fact that Trump is no longer in office.

The Durham appointment by then-Attorney General William Barr in 2019 was designed to examine potential errors or misconduct in the U.S. government’s investigation into whether Trump’s 2016 presidential campaign was conspiring with Russia to sway the outcome of the election.

A two-year investigation by Mueller established that the Trump campaign was eager to receive and benefit from Kremlin aid, and documented multiple interactions between Russians and Trump associates. Investigators said they did not find enough evidence to charge any campaign official with having conspired with Russia, though a half-dozen Trump aides were charged with various offenses, including false statements.

Until now, Durham had brought only one criminal case — a false statement charge against an FBI lawyer who altered an email related to the surveillance of Page to obscure the nature of Page’s preexisting relationship with the CIA. That lawyer, Kevin Clinesmith, pleaded guilty and was sentenced to probation.