In what seemed like a certainty after his office was raided by federal officials and records seized, President Trump’s personal attorney Michael Cohen has reportedly been cooperating with Robert Mueller’s investigators, including multiple meetings in D.C. and New York City over the last month, ABC News reports. So far, according to sources familiar with the meetings, Cohen’s hours of participation have reportedly been voluntary without any assurance of leniency or immunity. But Cohen and his lawyer Lanny Davis have appeared to be angling for a deal of some sort since Cohen’s shady post-election deals were revealed, leaving him facing years in prison with more potentially to come.

The fact that Cohen served as Trump’s fixer for a decade, including into the campaign and the Trump White House, makes his cooperation an extraordinary legal threat to the president. Cohen is already involved in a number of legal matters involving his work with Trump and beyond; last month he pleaded guilty to eight felonies as part of plea deal stemming from the investigation into hush payments made to Stormy Daniels and former Playboy model Karen McDougal ahead of the 2016 election. What Cohen knows about Trump’s Russia dealings, however, is more of a matter of conjecture at this point, although it seems reasonable to assume he has an intimate knowledge of Trump’s dealings with Moscow before and during the campaign.

Unsurprisingly, Mueller’s team zeroed in on Cohen’s knowledge of the Russia connection, touching “on all aspects of Trump’s dealings with Russia—including financial and business dealings and the investigation into alleged collusion with Russia by the Trump campaign and its surrogates to influence the outcome of the 2016 presidential election,” according to ABC News.

Cohen, of course, was mentioned in the Steele dossier as having traveled to Prague months before the election to meet with Kremlin officials to discuss alleged cash payments for the Clinton campaign email hack. It is a charge that Cohen has denied and Davis, his lawyer, denied again last month.

Cohen’s known Russia ties don’t stop there however, he also clumsily made overtures to Russian President Vladimir Putin’s spokesman, sending an email to a generic Kremlin email address in January 2016 soliciting help on a Moscow real estate project the Trump Organization was pursuing. “Over the past few months I have been working with a company based in Russia regarding the development of a Trump Tower-Moscow project in Moscow City,” Cohen wrote to Putin aide Dmitry Peskov. “Without getting into lengthy specifics, the communication between our two sides has stalled.” “As this project is too important, I am hereby requesting your assistance. I respectfully request someone, preferably you, contact me so that I might discuss the specifics as well as arranging meetings with the appropriate individuals. I thank you in advance for your assistance and look forward to hearing from you soon,” Cohen wrote.