The girl's stepfather and mother have been taken into custody on suspicion of murder by abuse.
The sheriff's office won't say how the girl died, only that she sustained injuries.
The girl has been identified as 15-year-old Jeanette Maples, a home schooled student registered with the Lane Education Service District.
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A call came in to 911 Wednesday night that Maples wasn't breathing. She was pronounced dead at the hospital.
The sheriff's office won't say who made the 911 call.
The sheriff's office took the girl's stepfather and mother, Richard McAnulty, 40, and Angela McAnulty, 41, into custody on suspicion of murder by abuse.
Investigators have been on scene at a Howard Avenue residence in the River Road neighborhood since Wednesday night and expect to be there all day Thursday.