President Donald Trump’s former national security advisor Michael Flynn may have started cooperating or negotiating a deal with the investigative team of special counsel Robert Mueller, multiple reports indicate.

According to The New York Times and The Associated Press, Flynn’s lawyers this week ended communications with the president’s legal team. They had previously been keeping in touch regarding the sprawling investigation into Russian influence on last year’s election.

The publications note that such contact would become unethical if it presented a conflict of interest, such as when one client has begun cooperating with prosecutors. Although the break-off of communications does not prove Flynn is cooperating with Mueller, the Times reports that Trump’s legal team suspects Flynn “has, at the least, begun discussions with [Mueller] about cooperating.”

Flynn resigned his position in February over his contacts with Russian ambassador Sergey Kislyak during the transition period. Mueller is also reportedly looking into allegations that Flynn and his son, Michael Flynn Jr., would have accepted a $15 million payment in exchange for sending Turkish president Recip Erdo?an his nemesis, the preacher Fethullah Gülen, who lives in exile in Pennsylvania.

Former acting attorney general Sally Yates said she had warned the White House that Flynn was susceptible to Russian blackmail over his contacts with Kislyak, which he apparently did not disclose to the Trump administration.

The Federal Bureau of Investigation started investigating Flynn’s business ties long before the Mueller probe began. Former FBI director James Comey said earlier this year that, before firing him, Trump had asked him to drop the Flynn investigation.

So far, the only publicly-known charges in Mueller’s probe are against Trump campaign chairman Paul Manafort, Manafort’s business partner Rick Gates, and former Trump foreign policy advisor George Papadopoulos. Papadopoulos definitely is cooperating with the investigators.

McClatchy revealed more ties between Manafort and Russia on Friday. It reports that Manafort flew to Moscow at least 18 times over a decade as a consultant, making “frequent contact with Vladimir Putin’s allies.” He also reportedly visited Kiev 19 times after the 2014 fall of Ukrainian dictator and Putin ally Viktor Yanukovych; Manafort was at the time working for a pro-Russian party called Opposition Block.