Answered my own question, I think:
February 21 1974-Heidi Peterson missing from Seattle WA - 4 or 5 years old-remains found 11 months later in a garbage can near her home.
No one ever tried or convicted, though the police had a suspect in mind. Too much time passed, evidence no longer available.
See Ann Rule's book, Kiss Me Kill Me excerpt:
http://books.google.com/books?id=72W...page&q&f=false