German officials included the offices of both Volkswagen’s CEO and the head of the Audi division when they raided company premises Wednesday, March 15 as part of an investigation into emissions fraud, according to a copy of the search warrant.

German prosecutors raided the headquarters of the two companies on Wednesday as part of an investigation into the group’s use of software to cheat diesel emissions tests in the U.S.

The warrant was first reported on Sunday by the German newspaper Bild am Sonntag. It does not identify Matthias Müller, Volkswagen’s CEO, or Rupert Stadler, head of the Audi, as suspects in the case.

Investigators do not yet have enough evidence to determine who is responsible for illegally manipulating diesel motor software to deceive American clean-air regulators, according to the warrant.

The warrant focuses on Audi’s role in the scandal, allowing officials to search company departments including sales, marketing, personnel, engine development and legal compliance, along with the executive offices. The document, which also included a map of Audi headquarters in Ingolstadt, Germany, names 47 people whose property is subject to seizure, including Müller and Stadler.

In a statement of facts, Volkswagen said that its employees programmed pollution control equipment in diesel cars to operate at a reduced level except when software detected that an emissions test was underway. As a result, the cars put out excess amounts of nitrogen oxides, which can cause respiratory diseases such as asthma and lung cancer.

Volkswagen pleaded guilty in a Detroit court this month to charges that included conspiracy to violate the Clean Air Act.

In a complaint unsealed in January, U.S. prosecutors alleged that Volkswagen’s executive managers in Germany were briefed in person about the emissions “defeat device” in July 2015, but chose to keep regulators in the dark.

Oliver Schmidt, a Volkswagen executive was arrested by the FBI for his alleged role in the company’s rampant cheating on emissions tests. Five other Volkswagen executives, who are all German, were indicted.

“It makes me concerned knowing that Volkswagen used ‘defeat devices’ to cheat the system. I drive a Volkswagen and was considering buying a newer model. I don’t think I’ll be buying a Volkwagen any time soon,” Morgan Nates said, a sophomore biology major from Atlanta.

U.S. prosecutors allege that the emissions scheme went on for nearly a decade. In 2006, Volkswagen engineers in Germany knew the company’s new 2.0 liter diesel engine was not capable of meeting emissions regulations.

Instead of going back to the drawing board, they designed a “defeat device” software function that allowed cars to detect when their emissions were being tested, and to boost performance during that time.

The scheme began to unravel when a group of scientists at West Virginia University discovered in 2014 that Volkswagen cars were emitting far more pollutants than the automaker claimed.

The CEO of Volkswagen Group, Martin Winterkorn, resigned in September 2015 after the scandal was made public. Volkswagen Group of America CEO Michael Horn has also left the company.

Winterkorn stands accused of knowing about the emissions cheating way before the company came clean. He is being investigated in Germany for fraud according to CNN Money.