Three US states announced lawsuits Tuesday against Volkswagen stemming from the German carmaker's emissions scandal.
Volkswagen admitted last September that it had installed software in about 11 million vehicles around the world that understated emissions during official tests.
The scandal led to the carmaker's first reported loss in more than 20 years, the resignation of chief executive Martin Winterkorn and a long line of investigations and lawsuits.
New York Attorney General Eric Schneiderman, Massachusetts Attorney General Maura Healey and Maryland Attorney General Brian Frosh joined the fray on Tuesday, charging that the manipulative software installed in VW's diesel vehicles undermined US environmental standards.
They allege the cheating was planned at the firm's highest levels - including by Winterkorn himself.
Volkswagen sold more than 25,000 vehicles equipped with the illegal "defeat device" in New York, more than 15,000 in Massachusetts and 12,395 in Maryland, according to the joint statement.
"The allegations against Volkswagen, Audi and Porsche reveal a culture of deeply-rooted corporate arrogance, combined with a conscious disregard for the rule of law and the protection of public health and the environment," Schneiderman said in the statement.
The lawsuits target Volkswagen, Audi and Porsche along with their US subsidiaries. They include charges of destroying evidence.