Former VW AG CEO Martin Winterkorn is facing a criminal investigation from German prosecutors after the automaker admitted it cheated on emissions tests in some of its diesel-powered vehicles.

Prosecutors in Braunschweig, Germany, have opened a criminal probe into Martin Winterkorn, after VW and others filed complaints calling for a criminal investigation to find those responsible for fraudulent measures taken to sell cars that didn’t meet emissions standards.

While the Volkswagen complaint didn’t name Winterkorn and the automaker’s supervisory board said last week that the former CEO “had no knowledge” of emissions-test data manipulation, prosecutors need to examine all possible leads.

In his resignation statement, Martin Winterkorn said that he was “not aware of any wrongdoing on my part.” Contacted by Bloomberg, VW spokesman Eric Felber declined to comment on the criminal probe, but added that the company generally supports investigations into the scandal.

The huge scandal has so far wiped €27 billion ($30.3 billion) from VW AG’s market value. German regulators announced that the carmaker must provide a plan by October 7 for some 2.8 million cars in the country to comply with the emissions standards, otherwise they may be pulled off the road.

While no longer VW Group’s boss, Martin Winterkorn remains a powerful figure inside the company. He is still head of Porsche Automobil Holding SE, which owns 52.2 percent of Volkswagen’s voting stock. In addition, he’s still chairman of Audi AG as well as the group’s truck holding company.

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