Former United States National Security Adviser Michael Flynn’s lawyers have broken ties with President Donald Trump’s legal team over special counsel Robert Mueller’s investigation into alleged interference by Russia in the US presidential election in 2016, The New York Times reported.

The move by Flynn’s legal team is an indication that he is either cooperating with the prosecutors or negotiating a deal, reported CNBC. Jay Sekulow, an attorney for Trump, told the channel that he was not surprised by the former national security adviser’s decision.

If Flynn cuts a deal, Mueller would get a behind-the-scenes look at the Trump campaign and the early weeks of the administration, The New York Times reported. Flynn, who had ties with Russia even before the election campaign began, was an early and important adviser to Trump and shaped the president’s populist “America first” platform. He was also the person in the transition team in charge of dealing with Kremlin.

Flynn resigned in February, barely a month after the Trump administration took over, after it came to light that that he had discussed the country’s sanctions on Russia with the then Russian envoy Sergei Kislyak. He is also being investigated by the Justice Department for failing to properly disclose his foreign business dealings.