Automaker FCA US pleaded guilty to conspiracy, admitting that it paid off leaders of the United Auto Workers to try to win concessions in negotiations covering thousands of factory workers.
FCA's conviction follows a series of guilty pleas from UAW officials who were showered with more than USD 3.5 million in cash and items of value from a jointly run training center over an eight-year period.
FCA stands for Fiat Chrysler Automobiles, which now is part of Stellantis, a company created by the merger of Fiat Chrysler and PSA Peugeot.
"FCA violated federal labor law and undermined the collective bargaining process and the faith of the UAW's membership in their leaders," said acting U.S. Attorney Saima Mohsin.
The head of FCA labor relations, Al Iacobelli, executed the scheme with five UAW officials and a spouse, especially General Holiefield, who was a union vice president.
He eliminated a USD 262,000 home mortgage in 2014 with training centre money.
Union officials used credit cards for spending sprees.
"Your honor, we plead guilty," FCA general counsel Chris Pardi told U.S. District Judge Paul Borman.
Iacobelli was sentenced to 5 1/2 years in prison in 2018, but the sentence was recently reduced by 18 months due to his cooperation.
Holiefield died in 2015; his wife pleaded guilty to a tax crime three years later.
Holiefield's successor, Norwood Jewell, was sentenced to 15 months in prison. His plea deal listed $60,000 in meals and golf paid with training center credit cards.
FCA will pay a $30 million fine to the government. An independent monitor will be appointed to oversee the end of the training center as well as handle other tasks.
The government's investigation became public in 2017, but agents soon were uncovering other corruption at the UAW.
Union dues were used to pay for golf, booze and vacation villas in California, and contractors were giving kickbacks for union business.
Eleven officials have been convicted, including former presidents Gary Jones and Dennis Williams. They are awaiting their sentences in Detroit federal court.