Audi CEO Rupert Stadler was arrested in Germany on Monday in relation to the dieselgate scandal, according to multiple reports.

The German authorities took Stadler into custody over concerns that he would suppress evidence. Munich prosecutors said Stadler's arrest was not made at the request of the U.S. Instead, it appears to be part of German prosecutors' widening probe into Audi.

Specifically, the authorities are investigating whether Stadler acted swiftly enough to halt deliveries of Audi models with defeat devices once the cheating had been discovered, a person familiar with the matter told Reuters. The defeat devices allowed Volkswagen, Audi, and Porsche 4-cylinder and V-6 diesel engines to emit illegal levels of pollution on the road than in government testing.

Stadler's arrest comes shortly after an executive restructuring at Volkswagen Group. Former CEO Mattias Müller, who took over immediately after the scandal broke in September 2015, was ousted as CEO in April and replaced by Herbert Diess.

Former VW Group CEO Martin Winterkorn, who was in charge when the dieselgate scandal became public, has been charged in the U.S. but not arrested because Germany typically doesn't extradite its citizens. Porsche powertrain boss Jörg Kerner also has been arrested by German authorities. Oliver Schmidt, a former VW engineer in the U.S., was sentenced to seven years in prison last year.

VW Group admitted it used the defeat devices, which amounted to software, to deceive regulators in the U.S. and Europe from 2006 to 2015. Thus far, the scandal has cost VW Group roughly $30 billion in buybacks, fixes, and fines, with more sure to come as Germany concludes its investigation.