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Authorities investigating the 1996 disappearance of college student Kristin Smart served searched warrants in California and Washington state for items they believe to be connected to the case.

The warrants were served last week for "specific items of evidence" at four locations, the San Luis Obispo County Sheriff's Office said in a statement.

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Two of the locations are in San Luis Obispo County and one is in Washington, and authorities told NBC News that the fourth is a home in Los Angeles County.

Kristin Smart was last seen in May 1996. FBI via AP

Smart, 19, vanished in May 1996 while returning to her dorm at California Polytechnic State University in San Luis Obispo, about 190 miles northwest of downtown Los Angeles. A friend said Smart had attended an off-campus party and was returning to the school with another student, Paul Flores.

Flores, who has been the subject of several police inquiries and searches, has never been charged in connection with the disappearance of Smart, who was legally declared dead in 2002.

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Late last month, the San Luis Obispo County Sheriff's Office said it had seized two trucks that belonged to members of Flores' family in 1996.

In September 2016, sheriff's deputies and FBI agents excavated a section of Cal Poly's campus. The department said at the time that "items of interest" were recovered and were being analyzed.

CORRECTION (Feb. 5, 2020, 9:20 p.m. ET): An earlier version of this article misstated when authorities said they had seized two trucks as possible evidence in the disappearance of Kristin Smart. The announcement was made last month, not this month.