Sergio Marchionne had been battling a "serious illness" for more than a year prior to his surgery.

Former Fiat Chrysler chief Sergio Marchionne was dealing with a long-term illness when he went in for surgery earlier this month, and the illness contributed to his death, according to multiple reports.

Marchionne had been receiving treatment for an unknown illness – an Italian publication reported he had shoulder cancer – for more than a year, according to University Hospital Zurich. The former CEO, who lived in Switzerland most of the year, was being treated for a “serious” illness, which he did not reveal to Fiat Chrysler officials.

The hospital released a statement, it said, in an attempt to eliminate any rumors about his care prior to his death.

“Mr. Sergio Marchionne was a patient at the USZ. Due to a serious illness, he came back for more than a year for treatment. Although all possibilities of cutting-edge medicine were exhausted, Mr. Marchionne unfortunately passed away. We deeply regret his death and express our deepest condolences to the family.”

(Former FCA CEO Sergio Marchionne dead at 66. Click Here for the story.)

An Italian publication, Lettera43.it reported that Marchionne “had been diagnosed some time ago with a rather invasive shoulder cancer.” Marchionne had complained of shoulder soreness for some time, taking cortisone shots to ease the pain.

Marchionne shown during an appearance with John Elkann, FCA chairman and Agnelli heir.

The publication further reported that he had a soft-tissue sarcoma and during surgery he suffered an embolism, and later slipped into a coma. The report said brain damage due to the embolism would have made it impossible for him to return to work if he emerged from the coma.

(Click Here for a look at the challenges facing new CEO Mike Manley.)

John Elkann, who basically worked in concert with Marchionne as FCA chairman and the leader of the Agnelli family, was unaware of the seriousness of the situation. Once he was informed, he traveled to Zurich and was told “there was no hope of recovery,” Lettera43 reported. Fiat Chrysler officials said they were unaware of his illness, saying that they were informed he had gone into the hospital for should surgery.

Then, “On Friday, July 20, the company was made aware with no detail by Mr. Marchionne’s family of the serious deterioration in Mr. Marchionne’s condition and that as a result he would be unable to return to work. The company promptly took and announced the appropriate action the following day.”

(To see more about FCA reporting lower earnings as it mourns Marchionne, Click Here.)

The Agnelli family, which controls Fiat Chrysler, appointed Mike Manley, who had been running the company’s Jeep and Ram divisions, to replace Marchionne as CEO. Manley had been considered the front runner to get the job when Marchionne retired at the end of this year. His first public actions as CEO were to call for a moment of silence during the company’s earnings call with analysts.