The San Luis Obispo County Sheriff’s office served four search warrants and detained the primary suspect Wednesday in the case of the disappearance of California Polytechnic student Kristin Smart, who vanished more than 20 years ago.

Police served four search warrants in two locations in San Luis Obispo County, one in Los Angeles County and one in Washington state, respectively, according to a press release.

Kristin Smart was a 19-year-old freshman at California Polytechnic State University in San Luis Obispo when she disappeared May 25, 1996. The prime suspect in the case, Paul Flores, has maintained his innocence but reportedly refused to cooperate with police.

On Wednesday morning, members of the Sheriff’s Office and the FBI were seen outside of the home of Flores’ mother in Arroyo Grande, and caution tape was posted to keep onlookers out, according to The SLO Tribune.

Another location was a home in a neighborhood where Flores himself has lived since 2010. Flores was detained during the duration of the search and then released, The Tribune reported.

Last Wednesday, the sheriff’s office announced that it detained two trucks in evidence that belonged to the Flores family in 1996.

KRISTIN SMART INVESTIGATION: CALIFORNIA POLICE SEIZE TWO VANS BELONGING TO FAMILY OF PRIMARY SUSPECT

Flores was the last person to see Smart after she left a party to return to her dorm. Flores claimed he dropped Smart off at her dorm room that night, but her roommate reported her missing two days later. Smart was never seen again, and a judge declared her legally dead in 2012, though her body was never found.

Since 2011, officials have recovered 140 new items of evidence, conducted 91 in-person interviews and submitted 37 items of evidence for modern DNA testing, last week’s press release said.

FAMILY OF KRISTIN SMART, WHO VANISHED 23 YEARS AGO, TOLD BY EX-FBI AGENT TO BE PREPARED FOR NEWS

The office also executed 18 search warrants, conducting physical evidence searches at nine separate locations, and carried out “a complete re-examination of every item of physical evidence seized by all agencies involved in this case."

Interest in the case was reinvigorated after Kristin’s mother, Denise Smart, told the Stockton Record that an FBI agent contacted her and told her to be ready for “a major development.” It was later revealed that Denise Smart spoke to a former FBI agent not currently working on the case.

Former San Luis Obispo County Sheriff Ed Williams previously said “there are no other suspects” than Paul Flores in Kristin Smart’s disappearance.

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In September 2016, the sheriff’s office and the FBI conducted a joint excavation of a hillside on the Cal Poly campus after announcing they’d found new information that suggested Smart’s remains could have been buried there. The agencies took away bones and other “items of interest” to a facility out of the county for analysis.