German prosecutors raided Volkswagen and Audi offices recently as part of an ongoing investigation into the diesel-rigging scandal.

Even as the criminal and civil cases against Volkswagen over its rigging of diesel engines wind down in the U.S., German prosecutors are ramping up their own probe – which could lead to additional criminal charges against current and former VW officials, including one-time CEO Martin Winterkorn.

The latest twist comes as the embattled automaker confirms that prosecutors had launched raids at VW headquarters in Wolfsburg, Germany, as well as the offices of its semi-independent Audi subsidiary near Munich.

“The execution of the search warrants is meant to clarify which persons were involved in the use of the relevant technology and, where applicable, were involved in providing inaccurate information to third parties,” said Munich prosecutor Ken Heidenreich, in a statement announcing the move against Audi’s offices.

In September 2015, Volkswagen was accused by the U.S. Environmental Protection Agency of rigging about 475,000 vehicles sold in the States using a 2.0-liter turbodiesel. A similar “defeat device” was subsequently found on another 80,000 VW, Porsche and Audi models using a more upscale 3.0-liter engine. The software was designed to detect when a vehicle was undergoing emissions testing and then temporarily reduce the production of noxious gases like oxides of nitrogen.

(VW brand profit slammed by diesel scandal costs. Click Here for the story.)

Since the scandal broke, VW has been forced to stop selling all diesels in the U.S. It has negotiated a series of settlements, most recently capped by last week’s guilty plea in federal court on criminal charges. Six of its executives have been indicted and it has agreed to pay about $25 billion in fines and other fees that include the buyback of more than 500,000 diesel vehicles.

But a separate series of investigations has been underway for more than a year in Germany. Prosecutors there are looking at a number of different potentially criminal violations, including allegations that top executives, such as Winterkorn, illegally withheld information about the scandal from investors.

(VW officially pleads guilty to felony charges in U.S. District Court. Click Here for the details.)

Until now, the issue has been centered in the town of Braunschweig, near VW’s Wolfsburg headquarters. But prosecutors in Munich began looking into Audi’s role in the scandal earlier this year. The luxury brand has largely escaped the damage the diesel rigging has caused the flagship VW brand – at least until now.

Munich prosecutor Heidenreich said his investigation focuses on the 3.0-liter diesel models Audi sold in the U.S.

(To see more about the guilty plea, Click Here.)

Audi is fully cooperating with authorities as we have the highest interest in clarifying matters,” spokesman Moritz Drechsel said, adding that he could not comment further due to the ongoing investigation.