Both Herbert Diess and Martin Winterkorn discussed defeat devices with engineers at a meeting

Recently-unsealed court filings are giving us a better insight into who at Volkswagen knew about what (and when they knew it) in the long-running Dieselgate emissions cheating saga.

Recently unsealed documents, reported by Der Spiegel and filed by the Braunschweig prosecutor's office, say Martin Winterkorn, Volkswagen Group CEO at the time, and Herbert Diess, current VW Group CEO and then-head of the Volkswagen brand, were present at a meeting about the cheating on July 27, 2015.

Winterkorn was Volkswagen Group CEO between 2005 and 2015. He resigned not long after Volkswagen admitted it installed defeat devices on certain diesels to beat laboratory emissions tests. Diess joined Volkswagen on July 1, 2015, having previously served as head of purchasing at BMW. He became Volkswagen Group CEO earlier this year.

Executives and senior engineers were at this meeting discussing how to deal with a threat from the USA's Environmental Protection Agency (EPA), which discovered certain Volkswagen diesels were emitting unusually high amounts of oxides of nitrogen (NOx), and threatened to withhold certification.

A court filing by Volkswagen's defence attorneys claims Diess was at the meeting to discuss how Volkswagen could convince US regulators to approve the vehicles. The newspaper says Diess was asked by Winterkorn if BMW, his former employer, had also used defeat devices. Diess reportedly said no.

A Volkswagen employee reportedly intervened when the two executives left the meeting with a copy of the presentation, stating it would be better if they didn't hold on to it.

Above: Herbert Diess, current Volkswagen CEO.

Volkswagen told the German newspaper, "The contents of the discussion, where Martin Winterkorn and Herbert Diess were present, cannot be fully reconstructed, because the recollections of the people who were present partially deviate."

In other court filings, the company claims it wasn't, at the time, fully aware of the depth of its problems, and only engaged lawyers four days after the meeting.

Volkswagen also argues it did not breach disclosure rules because it didn't believe fines would exceed €200 million ($314 million) based on historical precedent. The company didn't make an official financial disclosure until September 22, some 19 days after it admitted to using defeat devices.