A mystery left over from Mueller's Russia investigation just got solved
NBC's Hallie Jackson talking with Paul Manafort, Donald Trump's campaign manager, on the floor of the Quicken Arena in 2016. (Shutterstock)

Paul Manafort's longtime associate Konstantin Kilimnik was sanctioned by the U.S. government for providing polling data to Russian intelligence during the 2016 election.

The Russian-Ukrainian political consultant was indicted in 2018 as part of special counsel Robert Mueller's investigation for carrying out election interference on behalf of the Kremlin, and the Treasury Department state for the first time Thursday that Kilimnik had provided Russia with sensitive polling data before the 2016 election, reported Axios.

That completes a key link between Mueller's investigation and one conducted by the Senate Intelligence Committee, which found that Donald Trump's campaign chairman Paul Manafort tried to pass sensitive internal polling data and campaign strategy to Kilimnik.

The committee obtained some information that suggested Kilimnik "may have been connected" to Russia's hacking and leaking of Democratic emails, but those findings were largely redacted in the public report.

Kilimnik, who is wanted by the FBI for obstruction of justice, provided sensitive data to Russian intelligence as part of his efforts to blame Ukraine for the hacks and return former Ukrainian President Viktor Yanukovych to power.

Manafort, who was pardoned by Trump in the final weeks of his presidency, worked as a political consultant to Yanukovych for nearly a decade.