According to Hungary’s chief prosecutor, an investigation is underway, and the unnamed NAV official has already been heard by the Supreme Court of Hungary, hvg.hu reports.

Former tax official and whistleblower András Horváth (pictured), quit NAV in 2013 after alleging rampant fraud and saying he could not get an investigation of his charges. At the time, Horváth said he had a “green folder” containing all the questionable cases he encountered at NAV. State prosecutor Péter Polt reportedly said that the allegations in the folder are being investigated, and a verdict on the cases in question will soon be made.