Former Audi CEO Rupert Stadler was charged on Wednesday by German prosecutors in relation to the Volkswagen Group's diesel scandal, which first erupted in the fall of 2015.

Stadler was charged along with three others, whose identities are yet to be revealed, as part of a German investigation into the emissions-cheating scandal. The charges include falsifying certificates and illegal advertising of vehicles from the Audi, Porsche and Volkswagen brands, both in the United States and in Europe.

Stadler in particular was said to have known about the “defeat device” software at the heart of the scandal since at least September 2015 but failed to take any action to prevent the sale of vehicles with the software beyond the date. Prosecutors will now determine whether his case needs to go to trial, The New York Times reported on Wednesday.

Martin Winterkorn

Martin Winterkorn

He is the second senior VW Group exec to have been charged as part of the German investigation into the scandal. Former VW Group CEO Martin Winterkorn was charged in April by German prosecutors. Winterkorn was also charged in 2018 by U.S. officials in relation to the scandal, but since he resides in Germany, which doesn't normally extradite its citizens, he's been able to avoid questioning.

Stadler was arrested and imprisoned without charge in June 2018 because of fears he could suppress evidence. He was finally released in October of that year but had lost in job at Audi several weeks prior. His replacement was confirmed as Bram Schot in December 2018.

The fallout from the scandal has so far cost the VW Group $33 billion in buybacks, fixes, and fines in Europe and North America. While a number a number of individuals have been charged, so far only two have received prison terms, in both cases in the U.S. They include Oliver Schmidt who in 2017 received a seven-year prison sentence, and James Liang who that same year received a four-year sentence.