The Bellingham Herald reports Lt. Bill Hatchett says an autopsy determined that 23-year-old Mindy Rhoads died of smoke inhalation Wednesday night. Her body was found in the burned house.
Hatchett declined to discuss why investigators believe someone set the fire.
He says police are seeking several "people of interest."
A Border Patrol agent first spotted the fire and banged on the front door but no one answered. The agent called for firefighters but flames had engulfed the house by the time they arrived.
Hatchett says Rhoads didn't live at the house.