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This article is more than 1 year old

The former boss of Volkswagen (VW) and four other executives face up to a decade in prison after being charged with fraud by German prosecutors over the carmaker’s systematic cheating in emissions tests on diesel vehicles.

Martin Winterkorn resigned as chief executive in September 2015 after US authorities accused VW of deliberately manipulating its cars’ performance under emissions test conditions – meaning its vehicle emissions seemed much less polluting than in normal driving.

Winterkorn personally knew of the emissions cheating from at least May 2014, much earlier than he had admitted, the prosecutors alleged in a statement on Monday.

VW has already admitted that Winterkorn, aged 71, received a memo detailing the cheating in May 2014, but said he may not have read it.

While VW has previously pleaded guilty to corporate criminal charges, it has denied senior executives were directly involved, insisting it was limited to engineers.

However, prosecutors said Winterkorn approved the expenditure of €23m (£20m) on a “useless” software update which was designed to continue obscuring the real reason for the increased levels of pollutants from its cars in real-world conditions.

The alleged offences of Winterkorn and the other unnamed managers took place between November 2006 and September 2015, according to prosecutors in Braunschweig, near VW’s global headquarters in Wolfsburg, Germany.

The prosecutors said the indictment runs to 692 pages, plus another 300 file folders containing 75,000 pages of evidence against the accused. They face between six months and 10 years in prison if found guilty. The prosecutors are also seeking to confiscate between €300,000 and €11m in bonus payments, which were allegedly boosted by the emissions fraud.

Winterkorn is accused by the prosecutors of a “particularly serious case of fraud”, as well as breaching competition law. Winterkorn has previously denied wrongdoing.

The installation of “defeat device” software in VW cars to fool emissions tests has turned into one of the biggest scandals in German corporate history. The so-called dieselgate scandal has cost the company more than €27bn in fines in the US and Europe. VW has already apologised and pleaded guilty to criminal charges.

The software enabled 9m cars, including Volkswagen, Audi and Skoda models, to remain below legal limits for emissions of harmful nitrogen oxides when in test conditions, while continuing to deliver the performance benefits of less stringent standards on the roads.

Nitrogen oxides have been blamed for a global public health crisis, contributing to tens of thousands of premature deaths from heart and lung disease and strokes every year. Without the software, VW’s vehicles would not have been approved as road legal, the prosecutors said.

The fallout from the scandal has hit demand for diesel vehicles across other carmakers in Europe, amid evidence that nearly all diesel vehicles exceeded emissions standards in real-world conditions.

The Braunschweig action is one of a number of ongoing legal actions against VW and its former top executives over the dieselgate scandal.

Winterkorn and five other former executives have already been charged by US authorities with fraud, but they cannot be extradited from Germany to non-EU countries.

Former engineering executive Oliver Schmidt was imprisoned for seven years in the US for his part in hiding the software from regulators. He was arrested when attempting to return to Germany following a family holiday in Florida.

Last month the US Securities and Exchange Commission announced it was suing Volkswagen and its former chief executive, accusing them of defrauding investors by making “deceptive” claims about the environmental impact of its cars. Investors in Germany are also seeking damages over VW’s failure to disclose the issue.

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Another 36 people remain under investigation in Germany by the Braunschweig prosecutors. VW also faces a group litigation from British owners of its vehicles over alleged false misrepresentation of the cars’ emissions.

A Volkswagen spokesman said the company would not comment on investigations against individuals.

In a statement Felix Dörr, Winterkorn’s lawyer, said the prosecutors had not given the defence enough time to read and comment on new evidence presented in the indictment.