Gig Harbor Fire Department spokesman Eric Waters said the body of Dr. Thomas Babson was found Friday afternoon in a part of the home that was very difficult to access because of structural instability.
Waters says the body of Babson's 8-year-old daughter was found Thursday in a different part of the home.
The spokesman says fire investigators are working to determine the cause of the fire that started late Wednesday night.
Babson's wife, June, escaped the fire with their 12-year-old daughter, and a neighbor rescued their 8-year-old son, a twin. They were all treated for smoke inhalation.
Fox Island is near Tacoma.