A top Trump campaign official had repeated communications during the final weeks of the 2016 presidential race with a business associate tied to Russian intelligence, according to a document released on Tuesday by the special counsel investigating Russian interference in the election.
The campaign official, Rick Gates, had frequent phone calls in September and October 2016 with a person the F.B.I. trusts had active links to Russian spy services at the time, the document said. Mr. Gates also told an associate the person “was a former Russian Intelligence Officer with the G.R.U.,” the Russian military intelligence agency.
The special counsel, Robert S. Mueller III, is investigating numerous contacts between President Trump’s advisers and Russia-linked individuals and entities leading up to and after the November 2016 election. The document, filed in Mr. Mueller’s name, stated that the communications between Mr. Gates and the personal were “pertinent to the investigation.”
The individual is identified only as “Person A,” and the document describes him as someone who worked for Mr. Gates and Paul Manafort, Mr. Trump’s campaign chairman, as part of their earlier representation of Russia-aligned parties and politicians in Ukraine, including the former president of Ukraine. A person with knowledge of the matter identified Person A as Konstantin V. Kilimnik, who for years was Mr. Manafort’s right-hand man in Ukraine.
Mr. Manafort has told associates that he does not believe that Mr. Kilimnik has ties to Russian intelligence, but the document released on Tuesday shows that Mr. Gates told others of his history in the intelligence services. That history was widely discussed for years among people who worked with Mr. Manafort and Mr. Gates in Ukraine.
At the time of the calls, Mr. Gates was the Trump campaign’s liaison to the Republican National Committee and, before that, he was the campaign’s deputy chairman. Mr. Manafort served as the campaign chairman until August 2016, when he resigned amid the growing controversy about his work in Ukraine.
Both Mr. Manafort and Mr. Gates were indicted last year for money laundering and other financial crimes committed while, the charges said, they tried to hide the money they received for their Ukraine work. Last month, Mr. Gates pleaded guilty to financial fraud and lying to investigators and has agreed to cooperate with Mr. Mueller’s investigation.
Mr. Manafort has vowed to fight the charges. In February 2017, he told The New York Times he had “never knowingly spoken to Russian intelligence officers, and I have never been involved with anything to do with the Russian government of the Putin administration or any other issues under investigation today.”
But, he added, “It’s not like these people wear badges that say, ‘I’m a Russian intelligence officer.’ ”
Mr. Kilimnik was born in Ukraine when it was still part of the Soviet Union, and he served in the Russian Army as a linguist. Last year, as scrutiny mounted of his work with Mr. Manafort and Mr. Gates in Ukraine, he steadfastly denied any association with Russian intelligence. An investigation by Ukrainian prosecutors into Mr. Kilimnik’s possible links to Russian spy agencies was closed late last year without charges.
Mr. Kilimnik has maintained residences in Moscow and Kiev, the capital of Ukraine, and has traveled regularly between them during years of working for Mr. Manafort and Mr. Gates on behalf of various Russia-aligned oligarchs and political parties.
The new document is a sentencing memorandum for Alex van der Zwaan, a lawyer who pleaded guilty in February to lying to federal investigators about his conversations with Mr. Gates in 2016 about work the two men did in Ukraine.
Mr. van der Zwaan was an attorney at a firm that worked with Mr. Manafort and Mr. Gates to prepare a report used to defend Viktor F. Yanukovych, the former Ukrainian president, from international criticism over the prosecution and incarceration of one of his political rivals.
Mr. van der Zwaan “worked closely” on the report with Mr. Gates and Person A, according to a court filing submitted Tuesday night by Mr. van der Zwaan’s lawyers asking the judge for leniency in sentencing.
Mr. van der Zwaan originally told Mr. Mueller’s investigators that he had not spoken to Mr. Gates since August 2016, but subsequently admitted he had lied after prosecutors confronted him with evidence of conversations.
The sentencing document describes an observation by one unidentified witness in the investigation who said Mr. van der Zwaan had “gone native.”
“That is, he had grown too close to Manafort, Gates, and Person A,” the document stated.
According to the filing by his lawyers, Mr. van der Zwaan “had explored opportunities to leave Skadden to work directly for Gates and Manafort” in 2012 and 2013.