Berlin, September 29 (RHC)-- German prosecutors have launched an investigation of former Volkswagen CEO Martin Winterkorn over his alleged role in the company's emissions-rigging scandal.

The investigation will determine whether fraud was committed by Winterkorn through the sale of vehicles with manipulated emissions data, Braunschweig city prosecutors said in a statement on Monday. Prosecutors in Braunschweig, near VW's headquarters in Wolfsburg, have received about a dozen complaints, including one from Volkswagen itself, said spokeswoman Julia Meyer.

She said it was too early to say if and when prosecutors may try and interview Winterkorn himself, adding that she could not estimate how long the investigation would last. "This is a very broad case and in other such investigations it has taken many months, sometimes years," she said. Regulators in the U.S. had found "cheat" software in some diesel engines.

Winterkorn quit last week after almost nine years at the helm of VW, saying he had no knowledge of the manipulation of emissions results through the illegal use of so-called "defeat devices" to detect when a car was being tested and alter the running of its engines.

Volkswagen shares in the stock market have crashed since the scandal broke out. The company faces potential complaints and fines from courts and regulators.