Federal prosecutors in Virginia are reportedly probing a “secret Turkish lobbying effort” that previously involved former National Security Adviser Michael Flynn, who was recently given a lenient sentencing recommendation by special counsel Robert Mueller’s office for his help in several unspecified “ongoing investigations.” The New York Times reports Mueller had been handling the case but referred it back at some point to a “veteran national-security prosecutor” who is now overseeing the case. A grand jury is also reportedly expected to “hear evidence” on the case. Mueller’s office referred to Flynn’s “substantial help” in several probes in a sentencing memo released Tuesday, which led to a recommendation for Flynn to receive a sentence that does “not impose a term of incarceration.” Prosecutors reportedly started investigating Flynn’s ties to Turkey after he posted an op-ed in The Hill attacking Fethullah Gulen, a cleric living in the U.S. who has been accused of starting a failed coup against the Turkish government. Flynn reportedly called Gulen a “radical Islamist” and a “shady Islamic mullah” in the piece. According to the Times, investigators later learned Flynn’s company was paid $530,000 to investigate Gulen by a businessman with ties to Turkish President Recep Tayyip Erdogan.