The Volkswagen Group released a statement on Wednesday denying allegations made by former Chairman Ferdinand Piech regarding knowledge among the automaker’s senior staff of the diesel scandal before it became public in September 2015.

Piech, along with his extended family, is a major shareholder in the VW but resigned as Chairman in April 2015 due to in-fighting with fellow shareholders following a public dig made by him towards former VW Group CEO Martin Winterkorn.

Piech has largely remained out of the picture throughout the diesel scandal until recently when Germany’s Bild reported on comments made by the 79-year-old asserting that senior staff, including Winterkorn, who stepped down immediately after the scandal went public, knew about the issues months before admitting knowledge of it.

Martin Winterkorn

Martin Winterkorn

In its statement, VW said Piech had made similar accusations in 2016, though at the time internal investigators led by law firm Jones Day determined them to be “implausible.” The automaker also said it’s considering the “possibility of measures and claims against Piech,” perhaps hinting at some form of legal retaliation.

The latest news comes as German prosecutors are investigating VW over the scandal. As part of the investigation, Winterkorn in January testified before a German parliamentary committee where he again denied prior knowledge of the scandal.

Back in the United States, VW has pleaded guilty to three felony counts over the scandal and has agreed to fines, buybacks and other charges totaling close to $23 billion. Six of its executives have also been charged by the Justice Department, including one who was arrested.