Volkswagen's diesel scandal took a rancorous turn Wednesday when the board of directors denied news reports that former chairman Ferdinand Piech had given four members early warning about the U.S. probe into emissions cheating.
The board issued a statement that the four members "rejected all assertions made by Ferdinand Piech as untrue."
The reports, in the form of a pre-release of an article from the Bild am Sonntag newspaper and on the Spiegel Online website, say Piech told German prosecutors that he learned of the probe from an informant.
Piech asked CEO Martin Winterkorn about the matter in March, 2015, then told the four board members, according to the reports.
Winterkorn has testified in the German parliament that he didn't learn of the problem until shortly before U.S. investigators announced it in September, 2015.
The issue of who knew what and when is important, in part, because investors are suing in Germany, saying Volkswagen violated securities laws that required the company to give timely notice of any issue that could affect share prices. Volkswagen has said it met its disclosure duties.
The board statement said Piech gave the same account to internal investigators but that his statements didn't withstand scrutiny from law firm Jones Day, commissioned by Volkswagen to find out how the cheating happened.
"No evidence was forthcoming indicating the accuracy of these allegations, which were classified as implausible overall," the statement read.
It said the company "will carefully weigh the possibility of measures and claims against Mr. Piech."
Volkswagen has admitted installing engine control software that detected when cars were being tested, and turned the emission controls off during normal driving. The result was the cars emitted more than 40 times the U.S. limit for the pollutant nitrogen oxide.
The company has agreed to buy back or fix hundreds of thousands of cars in the U.S.; some 11 million worldwide were equipped with the deceptive software. U.S. authorities have charged seven former employees, and the company pleaded guilty to criminal violations. German prosecutors are investigating as well.
The board members who Piech reportedly told about the cheating were: Wolfgang Porsche, employee representative Bernd Osterloh, former IG Metall industrial union head Berthold Huber, and Stephan Weil, the governor of the state of Lower Saxony. The state is a shareholder. Wolfgang Porsche is also Piech's cousin.
Piech resigned in April 2015 after losing a boardroom battle with Winterkorn and his board supporters.
Piech had criticized Winterkorn in an interview, saying he was distancing himself from Winterkorn but not specifying why.