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Authorities say they believe a convicted serial killer who died in prison last year is responsible for the 1989 disappearance of Tiffany Sessions, while investigators unearthed a swampy area Thursday for the remains of the Florida college student.

Sessions, who attended the University of Florida, was last seen Feb. 9, 1989, as she left for an evening walk along her usual exercise route in the Gainesville area. Her body was never found.

On Thursday, deputies with the Alachua County Sheriff's Department announced they were actively searching for evidence and remains in the Sessions case, Fox affiliate WOFL-TV reported. Authorities could be seen scouring a wooded field in Gainesville, near where the young woman was last seen.

Detectives have identified 64-year-old Paul Rowles as the prime suspect in Sessions' disappearance and presumed murder. Rowles, a convicted murderer and rapist, died in a state prison last year.

The area being searched this week is close to where the body of college student Elizabeth Foster was found. Foster was raped and murdered in 1992 in what remained a cold case for years. But in recent months, authorities used advanced DNA testing to link Rowles to Foster, according to the Miami Herald.

Rowles was convicted and sentenced to life in prison in 1972 for the rape and murder of Linda Fida. Rowles, however, was released four years later after completing a sex offender's program, the newspaper reported. He was later sent back to prison to serve a 19-year sentence for the kidnapping and rape of a Clearwater, Fla., teenager, who managed to escape.

Eighteen months ago, when police used forensic evidence to link Rowles to Foster, they then questioned him in the Sessions disappearance. Rowles, who was terminally ill with cancer at the time, denied any involvement with Sessions and soon died in prison.

The Miami Herald reports that detectives seized a notebook belonging to Rowles after his death that provided a key clue in the case. Sessions' name was not found on any of the pages, but the date she disappeared -- 2/9/89 -- was scribbled in the book next to a "#2."

Detectives now believe Rowles was responsible for murdering both Foster and Sessions -- and that Sessions was his second murder victim.

"To me, the case is solved," the woman's father, Patrick Sessions, told the Miami Herald. "I’m convinced this is the guy who did it.”

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