A criminal charge has been laid in the U.S. Justice Department’s probe into the Volkswagen diesel emissions scandal.

A Volkswagen engineer pleaded guilty to conspiracy charges in a U.S. District Court in Detroit today, Reuters reports.The veteran engineer, identified as James Liang, pleaded guilty and entered a plea agreement. A DOJ spokesperson says part of the agreement includes having the engineer assist the government’s investigation into the automaker’s emissions cheating.

Liang, 62, has worked for the automaker since 1983 and was reportedly part of the team that developed the defeat device-equipped diesel engines. He left Germany to work for Volkswagen’s U.S. operations in 2008, around the time that the emissions-cheating 2.0-liter TDI models were being readied for sale.

Liang is charged with conspiracy to commit fraud against U.S. regulators and customers, and could face five years in prison. The indictment alleges that Liang conspired with past and current engineers to mislead government regulators. The engineer is reportedly cooperating with authorities, which now puts the heat on executives at the company.

According to Reuters, charges were laid against Liang in June, but the indictment was only made public today.

Volkswagen has already agreed to spend up to $16.5 billion to compensate U.S. owners and environmental regulators, as well as settle some state-level fines. A total of 475,000 2.0-liter diesel models are subject to a buyback program in the U.S.