A survey crew discovered the bones about 250 yards from the park, in the woods, police said.
An officer said the scene was “maintained overnight” and Washington State Crime Lab and the King County Medical Examiner’s Office helped Des Moines police detectives search and evaluate the area Wednesday.
The initial discovery was of just a few bones, the officer said, but they did find some more during the search Wednesday.
He said it was difficult to tell how old the bones are or the person’s age or gender from the remains.
The medical examiner will determine more upon examination, the officer said.