Kristin Smart's Family Is Cautiously Hopeful as Excavation Begins at Cal Poly

— -- Investigators in California have found several items of interest during a new search launched this week in hopes of finding the remains of college student Kristin Smart, who disappeared 20 years ago, according to police.

Smart was a 19-year-old freshman at California Polytechnic State University when she went missing after a party near school May 25, 1996. She was last seen early that morning.

Items were found at all three dig sites, which are located on the same hillside near Smart's dorm, said Tony Cipolla, spokesman for the San Luis Obispo County Sheriff's Office. The items are being analyzed to see whether they are connected to the case, which could take days, weeks or months, Cipolla said.

If investigators find that the items are related to the case, they will perform DNA testing on them, Cipolla said. The FBI was expected to wrap up the dig today, as planned, and they have two more locations to examine, Cipolla added.

Officials began excavating part of a hillside on campus Wednesday after receiving a lead that Smart’s remains might be buried there, the San Luis Obispo County Sheriff’s Office said.

Lindsey Smart Stewart was about to be a freshman in high school when her older sister mysteriously disappeared. Now, she’s a wife and a mother.

“Another year goes by, another birthday passes, another family engagement passes,” Stewart said in an interview with ABC News. “A lot has went by and every year it gets exponentially harder.”

FBI Detection dogs combed through the area in January and alerted authorities to "locations of interest" on campus. Investigators are also looking at several other locations that have not been disclosed, the sheriff’s office said.

San Luis Obispo County Sheriff Ian Parkinson told reporters the operation will last a few days.

In a statement obtained by ABC News, the Smart family called this week’s digging efforts “a crucial step in bringing our daughter home.”

“While we are hopeful and it is our fervent prayer for Kristin to be recovered and returned to our family with this effort, our hopes are tempered with the history of the last two decades,” the statement continued. "We are confident that the ‘person of interest’ will soon be held accountable for taking her life and harboring her remains for over 20 years."

The family is also pleading with the public to share any information about Smart's disappearance.

“Now is a great time to speak up,” Stewart told ABC News. “It might have been a little detail to them but when you put the pieces together in the puzzle, it could help solve the case and bring closure to my family.”

Stewart, who has an 8-month-old baby, said becoming a mother has given her new perspective on her sister’s disappearance, but it hasn’t made the grief any easier.

“I’m now a mother and I’ve seen the pain that my parents went through, my mother went through and what I went through, and it’s heartbreaking,” she said. “We’re really just looking for closure.”

ABC News' Emily Shapiro and Julia Jacobo contributed to this report. The Associated Press also contributed to this report.