Protesters are calling for the resignation of Orange County District Attorney Todd Spitzer.
Last week's demonstration was organized by family members of the eight people killed in the 2011 mass shooting at a Seal Beach salon.
Protesters claim the DA's office mishandled the prosecution of Scott Dekraai, who was sentenced to life in prison without parole.
They claim Spitzer ran for office saying he would not accept the misconduct of prosecutors but he never followed up on that promise.
Spitzer's office admits to "prosecutorial misconduct" in the Dekraai case, which was prosecuted under the previous DA Tony Rackauckas.
Sole survivor of Seal Beach salon shooting opens up for 1st time