Updated

Investigators excavating the land at a California university for the remains of a college student who vanished 20 years ago uncovered “items of interest” that were being examined Thursday to see if they were related to her disappearance.

Officials didn’t reveal what they found at California Polytechnic State University, San Luis Obispo, where 19-year-old Kristin Smart was seen returning to her dormitory from an off-campus party on May 25, 1996.

Paul Flores had told authorities he dropped off Smart near her dorm. He is considered a person of interest in the case, but has never been arrested or charged, authorities said.

The ongoing excavation began after a lead emerged through a comprehensive review of the case, Sheriff Ian Parkinson told reporters Tuesday. The two-decade investigation has involved other searches.

The unspecified items found this week were being analyzed to see if they are related to the case, San Luis Obispo County sheriff's spokesman Tony Cipolla said in an email.

“It could be days, weeks or even months before we know what we have,” Cipolla told The Tribune of San Luis Obispo.

The items were found on a hillside near a large concrete letter "P'' that is a landmark of the school, located halfway between San Francisco and Los Angeles. FBI agents and sheriff's employees began digging there Tuesday.

Two other sites also have been marked for digging, with work already underway at one.

Crews using heavy equipment then rakes and shovels were expected to sift through about 20,000 cubic feet of dirt through Friday.

Dogs trained to detect old human remains identified the three locations in January.

Smart's parents, Stan and Denise Smart of Stockton, told The Tribune of San Luis Obispo on Wednesday that they were encouraged by the developments, despite previous fruitless searches over the years.

"We are mindful that with or without the hoped-for results from this week's efforts, we are now on a path that will bring our family peace and comfort," they wrote in an email.

The Associated Press contributed to this report.