(Reuters) - A Volkswagen AG VOWG_p.DE executive charged in the automaker's diesel emissions scandal plans to plead guilty on Aug. 4 in U.S. District Court in Detroit, a court spokesman said on Tuesday.

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Oliver Schmidt, who was chief of Volkswagen’s environmental and engineering center in Michigan, has been held since January when he was arrested trying to return to Germany. Schmidt is one of eight current and former executives charged in the U.S. emissions probe.

Federal court spokesman David Ashenfelter said prosecutors and lawyers told U.S. District Judge Sean Cox on Tuesday morning that Schmidt had decided to plead guilty.

A lawyer for Schmidt, David DuMouchel, declined to comment. Schmidt was charged with 11 felony counts and federal prosecutors said earlier this year that he could face a maximum of up to 169 years in prison.

The terms of Schmidt’s plea agreement were not immediately clear. U.S. prosecutors have amassed more than 4.3 million documents covering more than 40 million pages in the ongoing probe.

In March, Volkswagen pleaded guilty to three felony counts under a plea agreement to resolve U.S. charges it installed software in vehicles to evade emissions tests.

Volkswagen spokeswoman Jeannine Ginivan declined to discuss Schmidt’s case and said the automaker “continues to cooperate with investigations by the Department of Justice into the conduct of individuals.”

Volkswagen has agreed to spend as much as $25 billion in the United States to resolve claims from owners and regulators over polluting diesel vehicles and offered to buy back about 500,000 vehicles.

Earlier in July, the Justice Department charged former Audi manager Giovanni Pamio with directing employees to design software enabling thousands of Audi diesel cars to beat U.S. emissions tests. He was arrested in Germany.

James Liang, a VW employee who pleaded guilty to misleading regulators, is cooperating with prosecutors and will be sentenced on Aug. 25.

Among those indicted earlier were Heinz-Jakob Neusser, former head of development for VW Brand and two former heads of engine development, Jens Hadler and Richard Dorenkamp.

Most of the Volkswagen executives charged are in Germany and may not travel to the United States since Germany typically does not extradite its citizens.

“It is now clear that Volkswagen’s top executives knew about this illegal activity and deliberately kept regulators, shareholders and consumers in the dark - and they did this for years,” said FBI deputy director Andrew McCabe in January. “We can’t put companies in jail but we can hold their employees personally accountable.”