Bernie Sanders struck a truce with the Democratic Party last summer which gave him wide latitude to rewrite the party platform in exchange for endorsing Hillary Clinton. Since that time he’s been mostly aligned with the Democrats in their fight against Donald Trump, both before and since the election. That fight now largely centers around exposing Trump’s illicit ties to the Kremlin. But there’s a missing piece of the Russia puzzle that Bernie is in a unique position to provide.

Bernie’s 2016 presidential campaign employed a chief strategist named Tad Devine. You may recall him from his previous high ranking roles in the campaigns of John Kerry and Al Gore. But what’s less widely known is that Devine also helped get Kremlin puppet Viktor Yanukovich elected as the Prime Minister of Ukraine. Also working on that same campaign: Paul Manafort, who was allegedly taking tens of millions of dollars under the table from a Kremlin intermediary at the time, and who went on to become the chairman of Donald Trump’s Russia-tainted 2016 presidential campaign.

How closely did Manafort and Devine work together on Yanukovich’s campaign? That’s rather sparsely documented. For instance this Slate article (link) confirms that they did both work for his campaign. According to this Politico article (link), they know each other well enough that Bernie’s campaign manager asked Devine to reach out to Manafort at one point to try to set up a Trump-Sanders debate.

But what’s not known is whether Tad Devine was aware, or has since become aware, that Paul Manafort was being paid off the books by the Kremlin for his work on that Yanukovich campaign. Moreover, with Yanukovich having been a Kremlin puppet, it’s fair to ask Devine how he was being paid for his own work on the campaign. In fact, considering how allegedly dirty Manafort’s relationship was with Yanukovich and the Kremlin during that campaign, one would think Devine would want to step forward and preemptively clear his own name.

If Bernie Sanders gained any incidental knowledge about Devine’s past relationship to the Kremlin during the course of working closely with him for several months on his campaign, he can help greatly by disclosing it. Even if Bernie has no such information, he’s in a position to publicly call on Devine to come forward and share whatever he knows about Manafort’s relationship to the Kremlin. Any such information could prove crucial to helping the FBI determine the role that Manafort and Vladimir Putin played in undermining the 2016 election.