Two men were arrested Tuesday morning in connection with the disappearance of Kristin Smart, the California college student who vanished in 1996, San Luis Obispo (SLO) County Sheriff Ian Parkinson said at a news conference.
Authorities have not found Smart's body, Parkinson said, but they have come across forensic physical evidence that they "believe it is linked to Kristin."
The sheriff talked to the family twice Tuesday, he said.
"I think they are feeling a bit of relief, but as you can imagine until we return Kristin to them, this is not over," he told reporters. "We have committed to them that we are not going to stop until Kristen has been recovered, no matter what the cause, no matter what the time, we're committed to that.
The family later released a statement calling it a "bittersweet day."
"It is impossible to put into words what this day means for our family; we pray it is the first step to bringing our daughter home," the family said. "While Kristin's loving spirit will always live in our hearts, our life without her hugs, laughs and smiles is a heartache that never abates."
"We are pleased that Kristin's case has now moved to the district attorney's office, where we know we will be in good hands, and look forward to the day when there will be 'justice' for Kristin," they said.
The two suspects have been booked into the San Luis Obispo County Jail, according to online inmate records.
Paul Flores, 44, has been booked on a murder charge, the records show. No bail amount is listed. Ruben Flores, 80, has been booked on an accessory charge and is being held on $250,000 bail.
The pair are expected to be arraigned on Thursday, though the elder Flores is eligible for bail. CNN has reached out to attorneys for both men.
Reached earlier by phone, Robert Sanger, an attorney representing Paul Flores, said he would not comment on "pending cases."
Last month, authorities searched Ruben Flores' home in Arroyo Grande. Flores' son, Paul, has remained the prime suspect in the decades-long missing persons case.
Smart disappeared on May 25, 1996. She was last seen near her Cal Polytechnic San Luis Obispo dorm, police said, after walking home from a party. Smart was declared dead in 2002.
Last year, investigators searched Paul Flores' home, and said they found "items of interest" on the property.
At that time, Flores was detained at his San Pedro, California, home and released back to his home after the search, Tony Cipolla, a spokesperson for the sheriff's office, said at the time.
Officials have said Paul Flores was the last person to see Smart on May 25, 1996.
Smart disappeared after she and other students walked home from a fraternity party.
She was last seen near her dorm, police said, but she never made it to her room. Friends and family never heard from her again, authorities said.
She did not have identification, money or extra clothing when she disappeared, police said.
A massive search and repeated interviews with a student who walked with her that night yielded no breaks, and Smart was declared dead in 2002.
In 2016, following leads indicating her body was buried on campus, the FBI flew in three cadaver dogs from its Quantico, Virginia, training facility, and investigators dug up part of the hillside near where the school's trademark "P" is embedded, to no avail.
Last year, the sheriff's office said it was working the case and provided a list of its efforts since 2011, when the present administration took the helm, including: performing 18 searches at nine locations; submitting 37 pieces of evidence for DNA testing; recovering "140 new items of evidence"; and conducting 91 interviews.