Herbert Diess is cleaning up Volkswagen's act

Sources suggest the company, slammed in 2015 for using trick software codes to cheat on its diesel emissions, is set to put a broom through its internal suspects.

The Braunschweig public prosecutor investigating Dieselgate has identified 39 culprits linked to the scandal, but VW itself has fired six managers and possibly more.

While there is no official word from the car maker about the firings, German newspapers Handelsblatt and Bild am Sonntag insist the most senior manager fired is former director of powertrain, Heinz-Jakob Neusser, along with former head of diesel development Falko Rudolph, diesel developer Rudolph Krebs and three other engineers.

More firings are expected from VW, which has largely used suspensions while its internal investigations have continued. Another former diesel development boss, Jörn Kahrstedt, is said to have been fired, along with an emissions specialist known only as Thorsten D.

Thorsten D could be a key in the German criminal investigation into Dieselgate, having declared to the Braunschweig public prosecutor that he informed current VW Group CEO Diess of the cheat on July 27 2015 — about six weeks before the crisis became public.

However, it’s unclear what Diess, who had just arrived from BMW, could have done about it, especially if he was surrounded and led by managers who might have been involved in the scandal.