US prosecutors have charged Volkswagen’s former chief executive Martin Winterkorn with conspiring to mislead the country’s regulators over a diesel emissions scandal. Winterkorn had maintained that he was not aware of any wrongdoing at the time of his resignation in September 2015. The indictment in a district court in Detroit says Winterkorn was twice informed about Volkswagen cheating US emissions tests before the scandal broke out in 2015. Winterkorn is charged with three counts of wire fraud and one count of conspiring to violate the Clean Air Act. If convicted, he may face up to 25 years in prison and a maximum fine of $275,000. If Winterkorn is in Germany, he is unlikely to be tried in the US as the German government rarely permits extradition requests for its citizens. US prosecutors have already charged eight VW managers in connection with the emissions scandal. While two have pleaded guilty, six have avoided extradition to the US by staying in Germany.