WASHINGTON (AP) — The star prosecution witness in the trial of a Hillary Clinton campaign lawyer testified Thursday that he was “100 percent confident” that the attorney told him he was not acting on behalf of a particular client when he presented information meant to cast suspicions on Donald Trump and possible links to Russia.

The lawyer, Michael Sussman, is accused of lying to the FBI about the fact that he was representing Clinton’s 2016 campaign interests and that of another client — although the campaign says it never authorized Sussman’s actions.

James Baker was the FBI’s general counsel in September 2016 when Sussmann scheduled a meeting to provide him with computer data that Sussmann said showed a potential secret communications channel between a Russia-based bank and the Trump Organization, the company of the then-candidate.

Sussmann is accused of lying to Baker during that meeting by saying he was not presenting the computer data on behalf of a particular client. In fact, prosecutors allege, he was representing the interests during that meeting of the Clinton campaign and another client, a technology executive who had provided him with the data.

Prosecutors allege Sussmann was not forthcoming about his Clinton ties because he assumed the FBI would consider the information less credible if it thought it was being presented with a partisan intent.

The Sussmann prosecution was brought by John Durham, the prosecutor appointed as special counsel during the Trump administration to investigate potential government wrongdoing during the early days of the investigation into Russian election interference and potential ties with the Trump campaign.

Defense lawyers have denied that Sussmann lied during the meeting and have suggested that it’s impossible for prosecutors to prove exactly what he said because only Baker and Sussmann were in the meeting and neither of them took notes.

But testifying Thursday, Baker said he was “100 percent confident” that Sussmann told him during the Sept. 19, 2016 meeting at FBI headquarters that he was not there on behalf of any particular client.

“Michael’s a friend of mine and a colleague, and I believed it and I trusted that the statement was truthful,” he said.

The data Sussmann presented purported to show furtive communications between a server of Russia-based Alfa Bank and a Trump Organization server. At the time the data was presented, the FBI was investigating whether the Kremlin and the Trump campaign were coordinating to sway the outcome of that November’s presidential election.

Given the existence of that investigation, Baker said, he took the information seriously as a potential national security threat and because Sussmann told him that the news media was intent on reporting on the data. He quickly alerted the FBI’s top counterintelligence official, thinking it could be another piece of evidence in the Trump-Russia probe and concerned that coverage of the cyber data could lead Russia to shift course.

“I already knew that we had an investigation going on of that nature, and here was another set of allegations relating to a different aspect of alleged interactions or connections between the Russian government” and the Trump campaign, Baker said.

He later added: “It seemed to me of great urgency and great seriousness that I would want to make my bosses aware of this information.”

Baker said he was led to believe by Sussmann that the material suggestive of a digital backchannel had been compiled by serious and respected cybersecurity specialists. The FBI assessed the data that Baker received and determined that there was no actual suspicious or secret contact between Russia and the Trump campaign.

There was, Baker said, “nothing there.”

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