Volkswagen’s former CEO Martin Winterkorn and an unnamed executive are being investigated over suspicions of market manipulation. The state prosecutor’s office in Braunschweig is looking into Volkswagen’s delay in informing investors about the emissions scandal and the financial repercussions. The investigation comes as a result of findings by the German federal financial supervisory agency, BaFin. Winterkorn who stepped down in September, said he took full responsibility for the scandal, though not personally culpable. Braunschweig confirmed that VW’s current chairman of the supervisory board Hans Dieter Pötsch is not being investigated, even though he was the finance chief during the scandal. Also being investigated are seventeen former VW employees, mainly comprised of low-level managers, on fraud charges.

German law requires publicly listed companies to inform shareholders of events and developments that might seriously affect the price of the stock. It was proven that though VW admitted to false emissions testing of 11 million diesel cars back in September, Winterkorn had been aware of it since at least May 2014. In a report from the board, the company alleges that it underestimated the scale of the problem in terms of the costs needed to rectify it and so expected to handle the issue in-house, without any serious effects to its shareholders. The company is facing a $46 billion fine from the US department of justice.