SIOUX FALLS, S.D. (Argus Leader) — Sioux Falls police say the motive in the fatal shooting of a pizza delivery driver remains unclear as authorities continue to search for a suspect. Authorities have not yet identified the Domino’s employee who died shortly after making a delivery to an east side home Wednesday night. Samantha Brinkman tells the Argus Leader she heard the gunshots outside her apartment and thought it was a car backfiring. Then she saw someone lying face down near the end of the driveway across the street. She and her boyfriend ran to help the victim and tried to stop the bleeding. Investigators combed the neighborhood Thursday for clues about the suspect who fled from the scene on foot.