It has been nearly two years since Volkswagen came clean and admitted its "clean diesel" engines were actually quite dirty.

In 2015, a VW engineer admitted the TDI diesel cars sold in the U.S. since 2009 were outfitted with "defeat device" software that let them pass emission tests, only to emit far more nitrogen oxides in real-world use.

Two years is a long time to implement damage control, which has cost VW Group $25 billion to date—but the story is continuing to unfold.

DON'T MISS: Lasting legacy of VW diesel scandal: EU gets serious about testing

A former Audi engineer has now stepped forward and implicated various VW Group executives in the scandal.

Zaccheo Giovanni Pamio, former head of thermodynamics in Audi’s engine development department, has suggested the knowledge of VW's wrongdoings goes further up the executive ladder than the company has previously admitted, according to The New York Times.

Pamio has been held in jail in Munich, Germany, since July. He reportedly told prosecutors that Audi managers were aware in 2006 their vehicles could not meet U.S. and European emission standards, which led to the implementation of defeat devices.

2013 Audi TDI range

2013 Audi TDI range

It seems clear subordinates like Pamio are not willing to take the entire blame for a scandal that may reach deeper than once imagined.

Audi has also been accused as one of several brands selling diesels in Europe that colluded to rig emissions and cooperate on emission-cheating technology.

Most recently, the Audi A8 V-6 and V-8 TDI have come under fire in Europe for potentially including illegal defeat devices.

READ THIS: Germany investigates possible Audi diesel emission cheats

The Italian engineer's defense attorney did not name the managers Pamio implicated when he spoke to prosecutors.

A handful of potential executives could be involved, up to the man who was CEO of VW Group at the time the scandal broke.

During the time to which Pamio referred, Martin Winterkorn headed the Audi brand—leaving to become chief executive of Volkswagen in 2007.

2013 Audi TDI range

2013 Audi TDI range

Winterkorn resigned in 2015 within days of the diesel scandal erupting in September.

Ruper Stadler replaced Winterkorn at Audi in 2007, and has remained at his position despite the investigations.

Authorities have not named Stadler a suspect at this time.

CHECK OUT: VW pleads guilty to felonies in diesel emission scandal

Matthias Müller was head of Audi product management until 2007; he then assumed the same position with the Volkswagen group.

He was selected to replace Winterkorn as Volkswagen CEO two years ago, and has been the public face of a company expressing contrition and vowing to launch up to 30 electric cars by 2025.

German authorities said 40 individuals are being investigated for ties to the Volkswagen scandal in Europe; investigations continue.


Follow GreenCarReports on Facebook and Twitter.