Officers responded to a report of a serious injury bicycle collision near the intersection of North Country Club Road and East 4th Street Monday night.
According to the Tucson Police Department, firefighters treated the male bicyclist was transported him hospital with life-threatening injuries.
The man passed away Wednesday at the hospital from his injuries. He has been identified as 54-year-old Santiago Diaz Jr.
Detectives with TPD determined that Diaz Jr. had entered a curb lane when he was struck. TPD says Diaz Jr. was not wearing a helmet.
The driver of the vehicle remained on scene and cooperated with the investigation. Neither speed nor impairments appear to be factors.