Millwall’s owner and chairman John Berylson died from injuries sustained after his car overturned and hit a tree in the United States.
Police in Falmouth, Massachusetts, say no other vehicle was involved in the crash on Tuesday.
Emergency services responded shortly before 08:00 local time and found Berylson, the sole occupant, trapped inside the car.
The 70-year-old was pronounced dead at the scene.
The cause of the crash – described by Millwall as a “tragic accident” – remains under investigation.
American businessman Berylson became a significant shareholder of Millwall in 2007 after he led a consortium which invested in the south-east London club, then in League One, and became chairman in October that year.
The Championship side hailed him as “a person of such remarkable generosity, warmth, and kindness”, while former players and rival clubs have also paid tribute.
Falmouth Police Department said preliminary investigations into the crash showed that Berylson was driving his Range Rover south on Sippewissett Road in Falmouth, a coastal town on Cape Cod, when it lost control on a curve and left the road.
The car then rolled over into a ravine and came to rest against a tree.
Berylson was trapped inside the vehicle and was “extricated by mechanical means”. He subsequently “succumbed to injuries received in the crash”.
The crash is being investigated by the Falmouth Police Department and the Massachusetts State Police.
Berylson, who lived in Wellesley Hills in Greater Boston, is survived by wife Amy and children Jennifer, James, and Elizabeth.
