Since the U.S. Environmental Protection Agency (EPA) announced in a news conference ten weeks ago that Volkswagen used illegal software to cheat emissions tests, the company has been under heavy scrutiny.
German prosecutors raided corporate offices, and Volkswagen has conducted its own internal investigation.
Now, it appears around 50 employees have come forward to testify as part of the probe.
Employees had until Monday to take part in an "internal witness program," a Volkswagen spokesperson told AFP on Tuesday.
Those who came forward to testify before the deadline were guaranteed to escape repercussions on the part of VW.
Volkswagen launched the internal investigation after being forced to admit that it installed "defeat device" software in an estimated 11 million cars worldwide.
2015 Volkswagen Passat TDI
Those limits were ignored in real-world driving, though. U.S. tests showed that certain models equipped with a 2.0-liter TDI engine emitted up to 35 times the legally-permitted amounts of nitrogen oxides.
The day after Volkswagen's deadline for internal witness testimony, the German Federal Motor Transport Authority (KBA) ruled that the software used to evade emissions tests was indeed illegal.
Volkswagen previously said that it didn't know whether the software in question constituted a "defeat device" under European rules.
In the 10 weeks since the EPA first announced that models equipped with the EA189 2.0-liter engine had "defeat device" software, Volkswagen CEO Martin Winterkorn and other executive have resigned, regulatory agencies on multiple continents have opened investigations, and civil suits have been filed.
Further investigations into Volkswagen, Audi, and Porsche models using a 3.0-liter TDI V-6 have also been opened.
2014 Volkswagen Beetle TDI
One of them qualifies as a "defeat device" too.
The carmaker recently submitted proposed fixes for the 2.0-liter TDI cars to the EPA and the California Air Resources Board.
However, details have not been made public, nor has Volkswagen discussed a timeline for initiating recall repairs of the affected cars.