(Reuters) — Fiat Chrysler said Wednesday it had reached an agreement to settle a criminal probe by U.S. prosecutors into alleged illegal payments to former United Auto Workers officials by former company employees.

Fiat Chrysler, which is now part of Stellantis NV, said it had agreed to plead guilty to a single count of conspiracy to violate the Labor Management Relations Act and pay a $30 million fine. The automaker has also agreed to an independent compliance monitor for three years.

The office of U.S. Attorney Matthew Schneider in Detroit said he would offer more details of the settlement later on Wednesday but confirmed Fiat Chrysler “has agreed to plead guilty and pay a $30 million fine.”

Last month, the UAW agreed to independent oversight to resolve a five-year federal corruption investigation that ensnared two former UAW presidents.

The U.S. attorney’s office said UAW had paid back over $15 million for improperly billing Ford Motor Co. and Fiat Chrysler for employing members who did not work at the training centers operated by the union and the companies.

U.S. Attorney Schneider’s office charged 15 former UAW officials as part of its investigation, and former presidents Gary Jones and Dennis Williams both have pleaded guilty to embezzling union funds.

Several UAW officers, including the two former UAW presidents, have pleaded guilty to embezzling millions of dollars for their personal benefit, using the funds to purchase expensive liquor and cigars and to pay for golf outings and related equipment, and to stay at expensive hotels.

The UAW represents about 400,000 U.S. workers, including workers at Detroit’s Big Three automakers and in other fields. At its peak in 1979, the union had a membership of some 1.5 million.

The investigation inquiry led to rival automaker General Motors Co. filing a lawsuit against Fiat Chrysler last year, accusing the Italian-American company’s executives of bribing UAW officials to secure labor agreements that put GM at a disadvantage.

A federal judge in Detroit in July dismissed GM’s lawsuit that Fiat Chrysler had called “meritless.” GM has asked a federal appeals court to reinstate the lawsuit.