A Volkswagen engineer pleaded guilty on Friday to conspiring to defraud regulators and car owners, in the first criminal charges stemming from the American investigation into the German carmaker’s emissions deception.

The plea by the engineer, James Robert Liang, a Volkswagen veteran, suggests that the Justice Department is trying to build a larger criminal case and pursue charges against other higher-level executives at the carmaker.

Mr. Liang was central in the development of software that Volkswagen used to cheat pollution tests in the United States, which the company admitted last year to installing in more than 11 million diesels vehicles worldwide. He was also part of the cover-up, lying to regulators when they started asking questions about discrepancies in emissions.

Mr. Liang’s admissions, made in the United States District Court for the Eastern District of Michigan, portray a broader conspiracy by executives, making Mr. Liang a potentially valuable resource for the developing criminal investigation. The Justice Department said Mr. Liang, who faces a maximum sentence of five years in prison, would cooperate.