Paul Flores "continues to be a person of interest in the disappearance of Kristin Smart in 1996," the San Luis Obispo County Sheriff's Department said in a statement.
The Los Angeles County Sheriff's Department assisted in serving the search warrant, which remained sealed, the news release said. No other details were immediately disclosed.
FBI looks to solve 20-year-old cold case near Cal Poly
San Luis Obispo County authorities in February served search warrants at four locations in the states of California and Washington.
Smart was last seen returning to her California Polytechnic State University dormitory from an off-campus party on May 25, 1996.
This is a developing story.
Editor's Note: The video above is from an earlier broadcast.