A business partner and former agent for Pro Football Hall of Famer John Elway has died after suffering an injury at a Southern California golf resort

Authorities are investigating the death of sports agent Jeff Sperbeck, a longtime friend and business partner of legendary NFL star John Elway. The sheriff’s office says 62-year-old Sperbeck died Wednesday morning from “serious injuries” he sustained after falling off a golf cart.

Jeff Sperbeck, 62, died after falling from the back of the golf cart over the weekend, the Riverside County Coroner confirmed to ABC News.