Winterkorn, who served as chairman of the board from 2007 to 2015, is the highest ranking Volkswagen official indicted in the government's three-year probe.
The computer program would detect when the car was undergoing emissions evaluations and decrease its nitrogen oxide emissions to comply with American standards. When the software recognized the car was on the road, however, it would allow emissions up to 40 times higher than standards permit.
According to the Winterkorn indictment unsealed today, the ex-CEO presided over the whole operation, including a "damage table meeting," in which employees outlined exactly how Volkswagen was deceiving U.S. regulators. Instead of ordering his subordinates to disclose the defeat device, Winterkorn instead allegedly "approved the continued concealment of the cheating software." the indictment says.
Winterkorn, then 68, resigned in 2015, just days after news of the scheme broke, saying in a statement "I am stunned that misconduct on such a scale was possible in the Volkswagen Group ... As CEO I accept responsibility for the irregularities that have been found in diesel engines and have therefore requested the Supervisory Board to agree on terminating my function as CEO of the Volkswagen Group. I am doing this in the interests of the company even though I am not aware of any wrongdoing on my part."
He's just the latest in a string of employees felled by the government probe. Two former VW engineers, Oliver Schmidt and James Liang, pleaded guilty and are serving time in prison. Five additional defendants were indicted last January, but like Winterkorn, are believed to be in Germany, which does not extradite its citizens to countries outside the E.U.
“We are reviewing the allegations and will take appropriate action,” an attorney for Winterkorn told ABC News.
Volkswagen did not immediately respond to ABC News request for comment.