The 53-year-old died Wednesday. A medical examiner's autopsy on Friday found he died from an air embolism and dialysis catheter removal. Pneumonia and metastatic stomach cancer were listed as secondary causes of death.
"My knee-jerk reaction was, "Oh my God, this wasn't supposed to happen," said Chicago attorney Gil Ross.
Ross has not been retained by the Tyree family, but does have decades of malpractice experience and has taken interest in their loss.
"In my opinion, based on my experience, for a patient to have a sentinel event -- a terminal, a fatal event -- resulting from an air embolism, secondary to the placement or removal of a catheter for dialysis, is what attorneys call 'res ipsa loquitur.' That means that the event speaks for itself. It does not happen in the absence of malpractice."
In a statement, the University of Chicago Medical Center said, in part:
"Everyone here is deeply saddened. We are grateful for Tyree's many contributions to the city of Chicago and to the Medical Center and are honored and privileged to have known and worked with him."
Tyree was chief executive and chairman of Mesirow Financial, an investment bank. His friend and successor at the company, which brought the Sun-Times out of bankruptcy, said the company and family is "devastated at the news."
"We are so sad we lost him for this reason. It seems so unfair," said Richard Price in a telephone conversation with NBC Chicago.
Price said the family is still too shaken to consider whether or not a lawsuit is going to be considered.
Tyree announced in October that he had stomach cancer and would undergo chemotherapy. He also suffered from diabetes and had kidney and pancreas transplants in 2006.
Old St. Pat's Church will be hosting Tyree's funeral. Services will be Monday, March 21. A wake will be held from noon to 7 p.m. with a funeral mass to follow.