Two associates of former Trump national security adviser Michael Flynn were charged Monday with acting as unregistered foreign agents in an alleged attempt to get Turkish cleric Fethullah Gulen extradited from the United States. The New York Times reports that Bijan Kian and Ekim Alptekin were both charged in Alexandria federal court for an alleged conspiracy to violate federal lobbying standards, and that Alptekin was also charged with lying to the FBI. This isn’t the first time investigators have probed this case: Last year, Robert Mueller examined an alleged plan by Flynn and his son to extradite Gulen in exchange for up to $15 million from Turkey, after Flynn published an op-ed calling Gulen a “radical Islamist” and a “shady Islamic mullah.” Investigators eventually learned that Flynn’s company had been paid $530,000 to investigate Gulen by a Turkish businessman with ties to President Recep Tayyip Erdogan.

The Turkish government has repeatedly sought to extradite the exiled cleric, whom they blame for a failed coup in 2016. On Sunday, Turkey’s foreign minister claimed that Trump had told government officials that he was working on extraditing Gulen, who has lived in the United States for more than two decades.