Troopers with Oregon State Police say they discovered a human skull inside a backpack.
The troopers were responding to a call from a cleanup crew from the Oregon Department of Corrections on Monday. They reported a "suspicious object" on the side of Interstate 5.
The troopers determined that the "suspicious object" was a human skull.
Police said the skull has no identifiable features but is most likely that of a female in her late 30s to 40s.
The Medical Examiner's Office is investigating in hopes of learning the identity of the person who died.