Four German-based employees of Volkswagen subsidiary Audi were indicted Thursday by a federal grand jury in Detroit in connection with the fuel emissions scandal.The four staff are accused of violating US clean air standards in the production of vehicles sold in the United States. In the indictment issued by the US District Court in Detroit, the four are charged with being part of a nearly decade-long conspiracy to defraud the US, to commit wire fraud and to violate the Clean Air Act, according to court documents. No hearing dates have been set. None of the defendants appeared in court. The Volkswagen company admitted in 2015 that it used software manipulations to make its cars seem less polluting.