Prosecutors working on the special counsel investigation into Russian interference in the 2016 election have linked Rick Gates, Donald Trump’s former deputy campaign chairman, to a person with ties to a Russian intelligence service. In a court filing released Tuesday night, prosecutors said Gates and the unnamed person, who had lived in Kiev and Moscow and worked for one of Paul Manafort’s companies, were in touch in September and October 2016—during the presidential campaign—and described the alleged link as “pertinent to the investigation.” It’s alleged that Gates knew about the person’s links to Russian intel services in the report, filed over the coming sentencing of Dutch lawyer Alex van der Zwaan, who pleaded guilty last month to lying to special counsel Robert Mueller's investigators about his contacts with Gates and the unnamed person. Van der Zwaan will become the first defendant in Mueller’s probe to face sentencing, on April 3.