The former head of labor relations at Fiat Chrysler Automobiles was indicted on conspiracy and other charges by a federal grand jury on Wednesday, accused of siphoning off millions of dollars from a workers training center to pay for lavish travel, gifts, home improvements and other expenses for himself and his main negotiating partner at the United Automobile Workers union.

The executive, Alphons Iacobelli, 57, who suddenly retired from Fiat Chrysler in 2015, used money the company put into a union account to pay for a $350,000 Ferrari 458 Spider, two gold Montblanc pens each worth $35,700, a swimming pool and new kitchen for his home in Rochester Hills, Mich., from 2012 to 2014, according to a 42-page indictment from the United States attorney’s office for the Eastern District of Michigan.

Also charged was Monica Morgan, the widow of General Holiefield, a U.A.W. vice president who led the union’s negotiations with Fiat Chrysler from 2008 to 2014. Mr. Holiefield came under scrutiny inside the U.A.W. in October 2013, when union officials began investigating hundreds of thousands of dollars in expenses and transfers linked to a union training center, according to the indictment. He retired in 2014 and died of pancreatic cancer the following year.

The indictment said Mr. Iacobelli authorized $1.2 million in payments for the benefit of Mr. Holiefield and his wife from 2009 to 2013. These included $262,219.11 to pay off the mortgage on a home owned by the Holiefields, as well as first-class plane tickets for Ms. Holiefield, and tens of thousands of dollars in cash transfers to companies she managed.