and five remained in Germany. The only one under arrest was Oliver Schmidt, who was seized over the weekend in Miami during a visit to the U.S.

Schmidt was in charge of VW’s compliance with U.S. environmental regulations. Those indicted also included two former chiefs of Volkswagen engine development and the former head of quality management and product safety.

Prosecutors said one supervised 10,000 employees.

All six were charged with conspiracy to defraud the U.S. by making false statements to regulators and the public. Three were also charged with fraud and clean-air violations.

Government documents say one engine development supervisor asked an assistant to search another supervisor’s office for a hard drive that contained emails between them. Then another assistant was asked to throw it away, prosecutors said.

Authorities said the scheme began when VW officials realized new diesel engines wouldn’t meet U.S. 2007 emissions standards. Acting on instructions from their supervisors, VW employees borrowed the defeat device idea from VW’s Audi luxury division, which was developing different engines with similar software.

In November 2006, some employees raised objections about the defeat device to the head of VW-brand engine development, prosecutors said. That official allegedly directed the employees to continue and warned them “not to get caught.”

In 2014, VW employees learned about a West Virginia University study that found emissions discrepancies in VWs. Three of the supervisors and other employees decided not to disclose the defeat device to U.S. regulators, prosecutors said.

In August 2015, a VW employee ignored instructions from supervisors and told U.S. regulators about the device.

VW also faces an investor lawsuit and a criminal investigation in Germany. In all, some 11 million vehicles worldwide were equipped with the software.