Kristin Smart was a freshman at Cal Poly when she vanished over Memorial Day weekend in 1996.
It's not the only unsolved case in San Luis Obispo County, but it has been the most high-profile mystery since the 19-year-old vanished on May 25 of that year.
"We'd do anything to get our girl back," said Denise Smart, Kristin's mother, in 2006.
The case gained national media attention as reporters told and retold the story of the blond, brown-eyed freshman who had disappeared from outside her Muir Hall dormitory about 2 a.m. after a fraternity party.
Never miss a local story.
The 6-foot-1 speech communication major had been drinking heavily and was last seen walking back to her dorm with fellow student Paul Flores. Three days later, Smart was reported missing.
Though he has never been arrested or charged in the case, Flores is considered by investigators to be the only constant suspect.
For more than a decade, scores of volunteers and authorities sifted through landfills, dug up back yards, combed through front yards and waded into marshes in San Luis Obispo County.
Crawl spaces at Cal Poly were searched. A grand jury investigated. The FBI was called in, and civil lawsuits were filed.
And the oldest of Denise and Stan Smart's three children has not come home.
The Stockton couple believes she is buried somewhere in this county.
Smart believes her daughter went to a party and someone laced her drink with a drug. It's the story she's heard the most, and it's easier to believe than the alternative, that of a brutal killing.
Despite ongoing devotion to the case, the family's biggest fear is that people will forget.
"I think that's the biggest fear of any parent of a missing child," Smart said, "that your child is forgotten."