A plea hearing will be held later this month in Adams County for the driver accused of hitting a pedestrian while he was looking at his cell phone.  Forty-two-year-old Matthew Olson is charged with homicide by negligent operation of a vehicle, homicide by a vehicle using a controlled substance, and hit-and-run.  The accident happened last year on May 18th in the town of Big Flats.  Eighteen-year-old Allison Joy Frystak was killed as she walked along State Highway 13.  A man who was walking will the victim says he saw the vehicle swerving just before hitting her.  Olson admitted huffing a chemical before the crash.