The New York Times has obtained internal e-mails and memos from Volkswagen Group that may suggest that top executives within the company were aware as early as 2014 that many of their diesel vehicles had illegal emissions control-cheating software.

Volkswagen has maintained that only a small number of engineers knew about the emissions-cheating software that has been found on Volkswagen, Audi, and Porsche diesel vehicles. The company has said that Martin Winterkorn, the CEO of Volkswagen Group when the scandal broke, did not know that any illegal software existed on US cars. Winterkorn stepped down from his position shortly after the news of the company’s wrongdoing broke.

If executives were aware that their cars had emissions system cheating software on them before the US Environmental Protection Agency (EPA) notified the company that it was in violation of federal rules, Volkswagen Group could face harsher fines and penalties for failing to disclose to shareholders issues that could materially affect the company’s stock price.

In September 2015 the EPA said that nearly 500,000 Volkswagen vehicles were illegally disabling emissions control systems when the cars were being driven under normal conditions (as opposed to being tested in a lab), but the company later admitted that the illegal software existed on about 11 million cars worldwide.

According to The New York Times, Winterkorn received an e-mail from Bernd Gottweis, a retired Volkswagen executive, in May 2014 "warning that regulators might accuse the carmaker of using a so-called defeat device—software that recognized when the car was being tested for emissions and activated pollution-control equipment.” Gottweiss apparently told Winterkorn that he’d have trouble explaining to US regulators why emissions from the diesel vehicles were “dramatically elevated.”

Volkswagen officials with knowledge of the matter told The New York Times that Gottweis’ e-mail was not specifically acknowledging the presence of defeat devices on the Volkswagen cars, but instead using strongly worded language to "get the attention of top management.”

In addition, when the EPA first found irregularities in Volkswagen’s emissions control systems in spring 2014, the company issued a voluntary recall to help its customers fix the issues, but documents reviewed by The New York Times "seem to indicate that Volkswagen officials already knew that no technical solution was possible.” The Times writes:

For example, an internal Volkswagen presentation dated late April 2014—soon after tests by specialists at West Virginia University raised questions about emissions by VW cars—discussed various strategies the company could use in response. One option was for Volkswagen to offer to update the engine software. But the update would not bring emissions down to the required levels, the presentation said. Nevertheless, Volkswagen carried out a voluntary recall in December 2014 to update the vehicle software. Subsequent tests by California regulators determined that the update had not fixed the emissions problem. … Other documents from 2014 and 2015 show Volkswagen managers weighing the risks of different strategies, which ranged from refusing to acknowledge that there was a problem to admitting there was a problem and even buying back diesel cars sold in the United States.

In Europe, Volkswagen has begun to recall its affected diesel engines to issue a 30-minute software update and, in some cases, install a small piece of hardware. Emissions standards are much stricter in the US, and Volkswagen has not yet been able to put forward a satisfactory recall plan that the EPA and the California Air Resources Board (CARB) can agree on. In January, German paper Sueddeutsche Zeitung reported that Volkswagen assumes it will have to buy about 115,000 cars back from their owners to make good with US regulators.

The Department of Justice has sued Volkswagen for billions of dollars for violating the Clean Air Act.