How the Volkswagen case unfolded

2014: A group of West Virginia University researchers observes that a Volkswagen Passat and a Jetta, cars that passed emissions tests in lab settings, were exceeding emissions limits by a factor of as much as 35 while on the road.

2015: The U.S. Environmental Protection Agency accuses Volkswagen of violating federal clean air rules. One study has suggested emissions caused by the defeat devices, as they are known, would cause nearly 60 premature deaths in the U.S.

January 2016: The U.S. Justice Department, acting on behalf of the EPA, sues Volkswagen. That March, the company also is sued by the Federal Trade Commission for the environmental claims about its vehicles.

January 2017: The Justice Department announces $4.3 billion in criminal and civil penalties and arrests six Volkswagen executives for their alleged connection with the scandal.

August 2017 :A Volkswagen engineer is sentenced to 40 months in prison and a $200,000 fine.

December 2017 :A former general manager of the company’s environmental office in Michigan is sentenced to seven years in prison and a $400,000 fine. A corporate compliance monitor will watch Volkswagen for three years under the terms of its probation.