Shannon House was last seen October 11, 2015 while working on a private property in Trinity County, California.
This past March, new evidence led investigators to re-examine the death of 23-year-old Georgia man Timothy Coggins, whose case went cold for more than 30 years.
Ruth Parker last saw her sons CJ and Billy Vosseler on Oct. 9, 1986, at her home in New Hampshire.
Elizabeth Hornbeck, a young mother of two, was last seen in Mountain View, Missouri on September 24, 2015.
Sheryl Ann Tillinghast was last seen at the Wassaic State School in Wassaic, New York 44 years ago.
Sara Taraskiewicz's body was found in the trunk of her car on September 14, 1992.
Matt Odom was found stabbed to death on September 15, 2014.
Clinton Nelson disappeared after leaving a friend's party on September 1, 2006.
Skylar Peterson-Tosic was last seen at his mother’s home in Escondido, California two years ago.
Jessica Phelps disappeared from her family's front yard on July 1, 1997.