The Ventura County Sheriff's Department released multiple surveillance videos Saturday night.
They say the videos show Darrin Stone, a service technician at the Pre-Trial Detention Facility, slashing the sign with a knife on more than one occasion. He has been placed on administrative leave.
Two others were also arrested, including Craig Anderson, an assistant with the District Attorney's office.
Anderson has since resigned.
Demonstrators topple statue of Junipero Serra, who help found missions in California, in DTLA
Demonstrators topple statue of Junipero Serra, who help found missions in California, in DTLA