AFTER 25 YEARS, HAS A FLORIDA SHERIFF'S OFFICE SOLVED ONE OF THE STATE'S BIGGEST MYSTERIES - WHAT HAPPENED TO TIFFANY SESSIONS?

"48 HOURS: THE LOST DAUGHTER" - MONDAY JUNE 2, 2014, 10:00 PM, ET/PT

After 25 years, has the Alachua County Sheriff's Office solved one of Florida's biggest mysteries - what happened to Tiffany Sessions? Tracy Smith and 48 HOURS investigate the disappearance of the college student and the search for Sessions in 48 HOURS: "The Lost Daughter," to be broadcast Monday, June 2, 2014 (10:00 PM, ET/PT) on the CBS Television Network.

It is a case that generated one of the largest searches in the history of Florida, driven in part by the missing woman's father, Pat Sessions, a marketing executive, who called on such folks as football great Dan Marino and politician Jeb Bush to get the word out about his daughter.

48 HOURS has been reporting on Sessions' disappearance for more than five years. What is known for sure is that on Feb. 9, 1989, Sessions, a student at the University of Florida, left her home around 4:45 PM and told her roommate, Kathleen Frezza, she was going for her daily walk. What is unknown is what happened next.

An hour after Sessions left home, Frezza began to worry because Sessions wasn't back. "I went out in the car. I drove around the route to see, I don't know, maybe she fell down and hurt herself," Frezza tells 48 HOURS. "But nothing."

The disappearance also drew the attention of Sadie Darnell, then a police officer and now the Alachua County Sheriff, who vowed to get answers for the Sessions family.

Pat Sessions vows to search until the day he dies. "How do you not look for your kid?" he tells 48 HOURS. "I can't stop."

"I thought we would find her in 24 hours. And then 24 days. And then 24 months," says Wayne Black, a private investigator hired by the family. "I never thought 24 years we would still be here."

The case has haunted family members and the community around Gainesville, Fla. At the time of her disappearance, police launched a massive search - considered the largest in the state at the time - that turned up nothing. And over the years since, there have been occasional leads, but none panned out. That changed in 2013, when Detective Kevin Allen began investigating the Sessions case. Allen learned that three years after Sessions disappeared, Elizabeth Foster, another 20-year-old student, was found murdered and buried less than a mile away from where Sessions lived.

Could Sessions have been buried in the same location? And was Paul Eugene Rowles, the man convicted of killing Foster, responsible for Sessions' disappearance? Rowles denied having anything to do with Sessions' case. However, police found Rowles' phonebooks, which included enough cryptic references to Sessions, to name him a suspect in her disappearance and presumed murder in 2014.

48 HOURS was there as members of the Alachua County Sheriff's Office excavated the trees and underbrush where Foster was found 22 years ago with the hopes of finding a clue to Sessions' fate. "As painful as this is, especially for family members, it's rewarding to know we're doing something," says Darnell.

"I think he solved the case," Pat Sessions says of Allen. "I think we've found who took Tiffany, I believe that."

Smith and 48 HOURS report the story through interviews with Sessions' parents, her friends and investigators. 48 HOURS: "The Lost Daughter" is produced by Chris Young Ritzen. Aimee deSimone is the associate producer. Joan Adelman, Gary Winter and Doreen Schechter are the editors. Peter Schweitzer is the senior producer. Susan Zirinsky is the senior executive producer.

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