A longtime friend and agent to former Denver Broncos quarterback John Elway has died after he reportedly fell off a golf cart that was being driven by Elway.

Jeff Sperbeck, 62, died early Wednesday morning, four days after he was injured, the Riverside County, California, coroner said.

On Saturday, Sperbeck was leaving a party with Elway in La Quinta when he fell from the golf cart that Elway was driving, TMZ first reported. Sperbeck, who had been sitting in the passenger seat, reportedly hit his head on the asphalt during the fall. He was rushed to a hospital and placed on life support but was pronounced dead days later.

Sperbeck and Elway worked together starting in the ’90s, with Elway and the Broncos winning the Super Bowl in 1998 and 1999.

Following his football career, Sperbeck and Elway remained friends and formed a wine company together in 2013 called 7Cellars.

“In 1990 Sperbeck became the manager of John Elway’s marketing and business activities and has been involved in a multitude of Elway’s and other athletes’ businesses, as an advisor, partner and, or investor,” the 7Cellars website says of Sperbeck. “It was the success of Elway’s restaurants that led he and John to the idea and conception of 7Cellars, as they saw a need for quality wine that was as top tier as the Elway’s brand.”

The Riverside County Sheriff’s Department is investigating the incident.