In December, ByteDance confirmed that it fired four employees who had used TikTok to spy on the locations of two journalists. Now, Forbesreports that the FBI and the Department of Justice have been investigating the incident.

News of the investigation comes at a moment when ByteDance is facing mounting pressure to sell its stake in TikTok. The company confirmed that US officials have said that TikTok will face a possible ban in the United States if ByteDance doesn’t separate itself from the video app.