Mary Day, 13, went missing in California in 1981. Her disappearance went unreported for over a decade. Her parents said she ran away, but her two sisters suspected Mary was murdered. Fifteen years later, the case took a turn when investigators began looking into it after one of her sisters alerted authorities. Maureen Maher brings new insight into the case for a new "48 Hours" airing Saturday at 10 p.m. ET.
