The department shall not dismiss a complaint unless the complainant withdraws the complaint or the department determines after a thorough investigation that, based on the facts, no reasonable cause exists to believe that an unlawful housing practice, as prohibited by this part, has occurred or is about to occur.
Source:
Section 12981.1, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=GOV§ionNum=12981.1..