Helena, MT -

Officials in south-central Montana have filed charges against a 31-year-old Washington state woman after a man was struck and killed on Interstate 90 near Big Timber last month.

Wyran V. Young of Oak Harbor, Wash., is charged with failure to remain at the scene of a fatal accident in Sweet Grass County and tampering with evidence for washing the man's remains off the pickup at a car wash about 40 miles away in Park County.

Park County Attorney Brett Linneweber says Young was served with the charges Tuesday. She was ordered to appear in District Court in Big Timber on Dec. 10.

Officials are still investigating the cause of death for 81-year-old Elgie Bedford of Wasilla, Alaska. Investigators have said it appeared Bedford he was struck by several vehicles.