Duerson played at Notre Dame and for the Super Bowl Champion '85 Bears. He also won a Super Bowl as a member of the New York Giants in 1993 before he retired.
The Miami-Dade County coroner's office confirmed the Thursday-night death but has not determined a cause.
His football life was filled with accomplishment, and so was his life apart from and after football. He was an ambassador for many charitable causes and had many friends.
But Duerson also had some tough times in recent years - a business failure, a home in foreclosure, and Thursday was the last edition of a weekly Internet radio sports talk show that he hosted.
Duerson was a whale of a football player - a four time pro-bowler, strong safety on the Bears' 86 Super Bowl champs, 11 years in the NFL, a two-time All-American at Notre Dame. Years later, he would serve as a member of the university's Board of Trustees.
Off the field, Duerson earned a Harvard MBA. He became part-owner of a company that supplied sausage to fast food chains. Nine years ago, he sold his stake and set out to start his own company.
Four years later, though, Duerson Foods went out of business. The following year, Duerson's Highland Park home was in foreclosure, and he filed for divorce from his wife of 24 years.
Duerson had settled in Miami. He was working as a consultant and hosted an Internet radio sports talk show called Double Time with Double D on Voice America.
On one of his shows late last month, he fondly reminisced about The Bears and Super Bowl 20.
"Happy anniversary to my teammates, my coaches, to all the Bears fans, to anybody associated with the game of football because that was special. Absolutely special," he said.
Duerson's body was found in his Sunny Isles Beach, Florida. His teammates and friends are stunned.
"It's been an up and down kind of day. It's been hard to focus on anything today," said former teammate Emery Moorehead. "He always had a plan, laid things out - like a game plan in the NFL. Double D did that and was very successful."
"This is such a surprise. He looked so fit. I didn't know he had anything the matter with him, so I don't know what happened," said former Bears coach Mike Ditka.
"When I lost Walter, he was the first there. When he lost his mother, I was the first there. Through all of it, his strength helped me through tough times, and we actually became like brothers," said Eddie Payton, Walter Payton's brother.
On Friday, the Bears released a statement on Duerson's death saying, "We are stunned and saddened to hear the tragic news regarding Dave Duerson. He was a great contributor to our team and the Chicago community. Today is a difficult day for all of us who loved Dave. We'll miss him. Our prayers are with his family."
His family said in a written statement, "Please remember Dave as a good, kind and caring man. He loved and cherished his family and friends and was extremely proud of his beloved Notre Dame, and Chicago Bears."
Duerson is survived by his four children.