Robert Liang, a German citizen who had worked as a Volkswagen engineer in the US for many years, had already admitted last September to working on the illegal software that the carmaker used to cheated on emissions tests.
Because of his confession, the public prosecutor's office was much more lenient than they otherwise would have been. Liang also worked with the authorities and gave them insights into "a company that lost its ethical way in the race for market share and profits."
Read more: 40-month jail worker for VW emplyoee
It should not be forgotten that the goal of massively expanding market share and overtaking Japanese competitors to become the world's largest automaker came directly from Martin Winterkorn. He became chairman of the Volkswagen Group in 2007, and with his resignation in September 2015, he assumed responsibility for the diesel scandal.
Today, Winterkorn still maintains that he had neither ordered the diesel fraud nor had he been informed about it. Although the prosecutor's office in Braunschweig near VW's headquarters followed up on initial suspicions against him, he has never been charged.
Proceedings have so far only been started against lower-level rank employees - five in Germany and two in the US. This fits in with Volkswagen's official narrative that ordinary software technicians are responsible for the illegal software. But this version has little to do with the facts which have come out in the past weeks.
For example, employees from all German car makers are accused of having secretly worked together to coordinate efforts on the diesel exhaust problem. Audi employees have been warning for years that the emissions manipulation could come out. And a former Audi engineer now sitting in jail claims that the company's leadership knew about the diesel scandal as early as 2006. Who was the head of Audi at the time? Martin Winterkorn.
Winterkorn's claim not to have known anything about the diesel scandal does not fit the image of a boss who looked into every last detail, an image he himself cultivated for years.
Read also: VW manager pleads guilty in Dieselgate case
In 2013, Winterkorn, acting as a detail-conscious leader, put on a show of inspecting a car for a journalist: "Then he looks at the car from the outside, he looks and looks, his nose is close to the hot metal, and what is that? At the edge of the hood the silver paint is thicker than usual. Winterkorn looks for his assistant with his eyes and gives him a nod."
It is unlikely that a boss, who was interested in the slightest irregularities in the paint, would have known nothing about a company-wide fraud.
A famous proverb says: "The little ones are hanged, the big ones run free." But we only have to look to South Korea to see that it is not always true. There, the heir to Samsung was sentenced Friday to five years in prison.
Whether Martin Winterkorn will ever have to stand trial is still an open question. But the probability increases with every new diesel scandal trial.