LIVINGSTON, Mont. -

A 31-year-old Washington state woman and her father have pleaded not guilty to charges related to the death of a pedestrian on Interstate 90 in southern Montana.

Wyran Young of Oak Harbor, Wash., pleaded not guilty Tuesday to leaving the scene of a fatal crash and tampering with evidence in the Sept. 30 death of 81-year-old Elgie Bedford of Wasilla, Alaska. Her father, 50-year-old Westley Young, pleaded not guilty to tampering.

Bedford was struck and killed between Big Timber and Greycliff. Prosecutors allege the Youngs' vehicle hit Bedford's body, but did not stop. Westley Young told investigators a semi-trailer in front of them hit Bedford first.

The tampering charges allege the Youngs stopped at a Livingston car wash washed their vehicle, leaving parts of Bedford's body at the car wash.