The New York Times reports Monday that former Volkswagen CEO Dr. Martin Winterkorn is being investigated by German prosecutors for possible violations of securities laws as part of the automaker’s emissions scandal.

In 2015, Volkswagen admitted that millions of diesel vehicles had been rigged to cheat on emissions testing.

Winterkorn resigned in the wake of the scandal admission after the EPA accused VW of manipulating emissions testing results.

Volkswagen continues to seek a fix for the affected vehicles after offering owners some financial compensation.