(Portland, OR) -- Police are confirming they've discovered the bodies of a missing Salem woman and her 3-year-old son. The Oregon State Medical Examiner says search crews found the bodies of 25-year-old Karissa Fretwell and her son Billy Fretwell Saturday in a remote wooded area of Yamhill County. Police say Karissa died from a single gunshot wound to the head. Investigators are still looking into how Billy died. Police arrested Billy's biological father, 52-year-old Michael Wolfe, late last month. Wolfe was indicted last week on charges of kidnapping and murdering the two.