Bernice Selby was 27 years old in 1962, living in a house on the shores of Lake Cassidy near Marysville, WA and finalizing the details of the divorce of her soon to be ex husband, Donald Selby. She was last seen in October of that year, but wouldn't be reported missing until 2 months later. Investigators had a pretty solid idea of who their main suspect was. Unfortunately, (natural) disaster caught them off course and they ended up with a solid theory, but no one to bring to justice.

Sources:

The Charley Project - Bernice Selby

Facebook - Missing - Please Find Us

Seattle Times - Thirty-three years ago, Bernice Selby vanished. She was never seen again., 1995