German public prosecutors said they had searched Volkswagen premises at its headquarters in Wolfsburg and in other places yesterday.

The prosecutor’s office in Braunschweig near Wolfsburg said the target of searches had been documents and data storage with regard to VW’s manipulations of diesel emissions.

The searches were carried out by three prosecutors helped by the German state of Lower Saxony’s office of criminal investigation, it said. Volkswagen said it was supporting the investigation and had handed over a range of documents.

Meanwhile the company’s top US executive said yester-day Volkswagen’s rigging of diesel emissions tests was not a company decision but the result of actions by a small number of engineers.

“To my understanding, this was not a corporate decision; this was something individuals did,” Michael Horn, president and CEO of Volkswagen Group of America, told a panel of US lawmakers investigating the German carmaker’s wrongdoing.

This was something individuals did

“I agree it’s very hard to believe, and I personally find it hard to believe,” he added. Almost three weeks after it confessed publicly to cheating US emissions tests, Europe’s largest carmaker is under pressure to identify those responsible and clarify exactly how and where the cheating happened.

The biggest business crisis in Volkswagen’s 78-year history has wiped more than a third off its share price, forced out its long-time chief executive, prompted investigations and rocked both the car industry and German establishment.

He told the House of Representatives Oversight and Investigations panel that he knew in 2014 the company might be breaking US emissions rules, because a study by West Virginia University had shown some of its diesel vehicles had high toxic emissions on the road. However, he added he did not find out that so-called “defeat device” software was used to manipulate emissions test results until “around September 3”, when the company admitted its cheating to US regulators.