The judge agreed with a change of venue motion made by the defense attorneys for Paul Flores.
RELATED: Kristin Smart case: Paul and Ruben Flores to stand trial next April
The 44-year-old was charged with first-degree murder in the killing that allegedly happened as he tried to rape Smart in his dorm room at California Polytechnic State University in San Luis Obispo.
His father, 80-year-old Ruben Flores, is charged with accessory to murder after the fact.
Both men have entered not guilty pleas.
RELATED: Kristin Smart case: Missing student killed during 1996 rape attempt, district attorney says
Kristin Smart case: Missing student killed during 1996 rape attempt, SLO DA says
Smart disappeared nearly 26 years ago after she was seen leaving a college party with Flores.
Her body has never been found.
The trial had been scheduled to start on April 25.