Assistant Sheriff Ryan Monaghan 
Sheriff of San Mateo County

Ryan was born in Southern California and raised in San Mateo County.  Ryan graduated from Serra High School in San Mateo.  After graduation, he continued to study at University of Nevada, Reno.  After a break in his higher education, Ryan earned a bachelor’s degree in Criminal Justice Management from Union Institute and University and master’s degree in Security Studies from the Naval Postgraduate School.

Ryan began his public service journey as seasonal employee for the City of San Mateo Harbor Patrol and as a police cadet with the San Mateo Police Department where he was hired as a police officer in 1994.  He spent the next 26 years working a variety of assignments including Patrol, Traffic, Street Crimes and Problem-Oriented Policing, and Investigations.  He was also a member of the Special Weapons and Tactics (S.W.A.T.) Team for 13 years and was an original member of the San Mateo Police Honor Guard and the San Mateo County Terrorism Counter-Assault Team (T-CAT).  In 2017, Ryan was recognized by the San Mateo County Board of Supervisors as a recipient of the Domestic Violence Council’s Barbara Hammerman Award for his countywide efforts in combatting domestic violence.

After promoting up through the ranks at San Mateo PD, Ryan was appointed as the Chief of Police of the Tiburon Police Department in 2021 where he served for the past two years before joining the San Mateo County Sheriff’s Office.  In Tiburon, Ryan was credited with implementing 21st Century policing practices that improved transparency, community engagement, and diversity in the department’s workforce.  Ryan was an active member of the Marin County Police Chief’s Association serving as treasurer, vice president, and president.  He also remains an active member of the California Police Chiefs Association.