Prosecutors said on Tuesday that Mr Winterkorn had known no later than May 2015 that the company could face serious penalties in the United States. Mr Pötsch was informed at the end of June 2015 and Dr Diess at the end of that July, prosecutors said. The three defendants withheld information from shareholders in order to protect the Volkswagen share price, prosecutors said. Volkswagen shareholders did not learn of the cheating until the Environmental Protection Agency issued a notice of violation in September 2015. Volkswagen's share price fell by almost half, and the cost of the scandal has since topped $30 billion in court settlements and fines.