Our mission is to protect and serve our communities by delivering professional policing and correctional services while upholding our commitment to public safety, community engagement, and organizational excellence.

About Us

Founded in 1856, the County of San Mateo, with the San Francisco Bay and Pacific Ocean making up the eastern and western most boundaries, covers over 500 square miles consisting of densely populated cities and rural farmland. Over 90% of the County’s 740,000 citizens reside in 20 incorporated cities.

The first Sheriff of San Mateo County took office in 1856 when the County was incorporated from parts of San Francisco and Santa Cruz Counties. As the chief law enforcement officer, the Sheriff is responsible for planning, organizing, directing, and reviewing the activities and operations of the Sheriff’s Office, including adult correctional facilities, rehabilitation, and re-entry services for offenders; public safety and emergency services; forensic laboratory services and specialized programs, such as narcotics, search and rescue, bomb detection and disposal and more. The Sheriff coordinates assigned activities with other County departments and outside agencies, and provides highly responsible and complex administrative support to the Board of Supervisors and County Executive Officer.

Today, the Sheriff’s Office has over 800 sworn personnel and professional staff who provide various policing services to all unicorporated areas of the County and to the following contract cities, towns and districts: Half Moon Bay, Millbrae, San Carlos, Portola Valley, Woodside, the Peninsula Corridor Joint Powers Board (Caltrain) and the San Mateo County Transit District (SamTrans). The Sheriff's Office also provides investigative services to the San Francisco International Airport.

The mission of the San Mateo County Sheriff's Office is to protect and serve our communities by delivering professional policing and correctional services while upholding our commitment to public safety, community engagement, and organizational excellence.

To review the Policy Manual, which provides the operating guidelines for the Sheriff's Office, please click here.

Also in this section

Administrative and Fiscal Services

Office History

1856
San Mateo County Sheriff's Office
The San Mateo County Sheriff’s Office was founded in 1856.
1857-1858
Sheriff John W. Ackerson
John W. Ackerson was elected as the first Sheriff of San Mateo County. Before being elected Sheriff, John Ackerson had previously worked for a lumber company. Sheriff Ackerson served for two years. After leaving the Sheriff's Office he went on to Puget Sound, Washington where he found much success in the logging and lumber industry.
1857
San Mateo Courthouse
The first San Mateo County courthouse and jail was J.V. Diller's warehouse located on Redwood Creek. In 1858 a new courthouse and jail was built and were located on Broadway Avenue in Redwood City.
1859
Sheriff Silas Hovius
Silas Hovius was elected as the second Sheriff of San Mateo County and served for two years. Prior to being Sheriff, he was a farmer on the coast.
1865
Sheriff Thomas W. Lathrop
Thomas W. Lathrop was elected Sheriff and was a first Lieutenant of the Jefferson Cavalry, a local militia. There were concerns that the Confederate army would march through San Mateo County on their way to the San Francisco Mint. Their intent was to stop the flow of gold to the Union. Luckily, the Confederate army was stopped 80 miles from the California border.
1930s
Sheriff James McGrath
In the 1930's, Sheriff James McGrath established a precedent by putting his only night patrol deputy in uniform. Deputy John O'Brien reported for duty wearing a khaki shirt, olive drab trousers, a police cap and a black leather coat with a gold badge. McGrath stayed in office for four terms, the longest tenure in San Mateo County Sheriff’s history.
1951
Modern Law Enforcement with Sheriff Earl B. Whitmore
Modern Law Enforcement with Sheriff Whitmore In 1951, Earl B. Whitmore was elected Sheriff and brought modern policing standards to the Sheriff's Office. At the age of 34, Sheriff Whitmore was the youngest Sheriff in the United States. Prior to 1951, the Sheriff was the only person of rank within the office. Sheriff Whitmore established a new rank system consisting of a Chief Deputy Sheriff, Chief Civil Deputy, Chief Jailer, Captain of the Criminal Division, Lieutenant in charge of the Juvenile Division, Supervisor of Records and Identification Bureau, six Inspectors and four Patrol Sergeants.
1953
Sub-stations at Mills Field
The Sheriff's Office increased in size from 54 to 91 employees. Sheriff Whitmore opened sub-stations at Mills Field (San Francisco Airport), Half Moon Bay, Sharp Park (Pacifica) and Brisbane to provide greater law enforcement coverage throughout the county. The first resident deputy was in Pescadero, which was the center of the south coast area, approximately 200 square miles. Sheriff Whitmore established standardization of police radios in all patrol cars.
1951-1973
Crash Wagons
One of the most unique innovations was the “Crash Wagon.” Five ambulances were outfitted with police protection, investigation and rescue equipment. Staffed with a Deputy Sheriff and an Ambulance driver, these vehicles patrolled the county on a 24/7 basis and were able to respond to any incident. Sheriff Whitmore received national recognition, including United-International News Reels' 1954 film “Crash Wagons.” The film was distributed throughout the United States including 37 foreign countries. A letter from J. Edgar Hoover the first Director of the Federal Bureau of Investigation of the United States commending Sheriff Whitmore, was included in the film.
1951-1973
Crime Lab
Sheriff Whitmore established a Crime Lab equipped with the latest and finest equipment for detection and examination of evidence. The services of the County Crime Lab were made available to all other agencies in San Mateo County.
1951-1973
Narcotics
San Mateo County was one of the first in the state to train deputies in the field of narcotics, working with local law enforcement apprehending “dope peddlers and users.” Sheriff Whitmore assigned four deputies to attend service groups and other organizations in the county giving talks on narcotics and to acquaint the general public with the “devil's weed.” It later evolved into the Bureau of Special Services, which investigated vice, narcotics, gambling and the growing juvenile delinquency problem.
1951-1973
Work Furlough Program
In 1966 the Sheriff’s Work Furlough Program was the first of it's kind in the United States, housing 110 inmates. Inmates that are convicted of minor crimes and employed could apply to this program. The program allowed individuals to attend work during the day and were able to stay at the correctional facility each night to serve out their sentencing. They paid for their own incarceration, saving the taxpayers thousands of dollars each year. The deputies at Work Furlough were trained in rehabilitation counseling and each was assigned 12 inmates for individual and group counseling.
1973
Sheriff Whitmore Retires
Sheriff Whitmore Retires: In 1973, after 22 years as Sheriff Earl Whitmore retired.
1973-1983
Sheriff John R. McDonald
Following Sheriff Whitmore’s retirement, the Board of Supervisors appointed John R. McDonald who was Chief of Police for the City of Redwood City to complete the duration of Sheriff Whitmore’s term. Sheriff McDonald went on to serve as Sheriff of San Mateo County for 10 years until he retired in 1983.
1983
Special Election
Because Sheriff McDonald retired before the end of his term, the County held a special election to fill the vacancy. Lieutenant Brendan Maguire, along with several other lieutenants and captains in the Sheriff's Office, ran for Sheriff. Brendan Maguire won the election and became Sheriff in 1983.
1986-1993
Sheriff Brendan Maguire
Sheriff Maguire ran again as the incumbent in the 1986 general election. The only other candidate was a man named Jim White, who had no prior association with the Sheriff’s Office. Two months before the election, Sheriff Maguire passed away. All members of the Sheriff's Office pulled together and campaigned for Sheriff Maguire. He was re-elected posthumously and Undersheriff Leonard Cardoza was appointed as Sheriff until a special election could be held. Several captains and lieutenants ran for Sheriff in a special election, and Leonard Cardoza was elected and continued as Sheriff until he retired in 1993.
1993-2007
Sheriff Don Horsley
Don Horsley began his public service career with the Daly City Police Department before becoming a juvenile counselor with the San Mateo County Probation Department and later a middle school teacher. He returned to law enforcement, first with the Pacifica Police Department and then with the San Mateo County Sheriff’s Office in 1972. In 1993, Horsley was elected Sheriff of San Mateo County, serving for 14 years before retiring in 2007. His tenure as Sheriff focused on innovative leadership and modernizing the training and tools available to deputies. He also founded the Sheriff's Activities League in 1997, strengthening relationships between youth, deputies, and communities. Following his retirement, Horsley was elected President of the Sequoia Healthcare District Board. In 2010, he returned to public service when he was elected to the San Mateo County Board of Supervisors.
2007-2017
Sheriff Greg Munks
Greg Munks, who served as Undersheriff to Don Horsley for 14 years, ran unopposed in the election shortly following Sheriff Horsley's retirement. Sheriff Munks was re-elected in 2010. In 2014 he was re-elected for his third term as Sheriff. In 2016, Sheriff Munks retired before the end of his third term. During his tenure as Sheriff, Munks successfully opened the new Maple Street Correctional Center. The Maple Street Correctional Center earned its LEED certification for its environmentally conscious design. This new correctional center aids the Sheriff’s Office in reducing recidivism with effective jail programs.
2017-2023
Sheriff Carlos G. Bolanos
Following Sheriff Munks’ retirement, the Board of Supervisors appointed Carlos G. Bolanos as Sheriff. Sheriff Bolanos had served as Undersheriff to Sheriff Munks for 10 years, and prior to that, served as the Redwood City Police Chief. During his tenure with the Sheriff’s Office, the agency began police service contracts with the cities of Half Moon Bay, Millbrae and San Carlos. Sheriff Bolanos oversaw construction of the new Siebel Firearms Range and the Sheriff’s Office Headquarters Building, expanded mental health services in the County’s correctional facilities, launched the Enhanced Crisis Intervention Team program, and implemented body-worn cameras for all sworn personnel.
2023-2025
Sheriff Christina Corpus
In January 2023, Sheriff Christina Corpus was sworn in as San Mateo County’s 26th Sheriff. Prior to being elected, she served as Chief of Police Services for the Millbrae Police Bureau. During her tenure as Sheriff, the Sheriff’s Office moved into its new Headquarters Building, located at 330 Bradford Street in Redwood City. The new building officially opened its doors to the community in June 2024. In October 2025, the Board of Supervisors voted to remove Sheriff Corpus from Office for cause pursuant to the County Charter.
2025
Sheriff Kenneth Binder
In November 2025, Sheriff Kenneth Binder was appointed by the Board of Supervisors and sworn in as San Mateo County’s 27th Sheriff. Binder, a policing leader with nearly three decades of service, has been recognized for his leadership, integrity and commitment to organizational excellence. Sheriff Binder considers serving as San Mateo County’s Sheriff the honor of a lifetime. He is committed to ensuring well-trained and professional delivery of public safety services by the men and women of the Sheriff’s Office, who are deeply devoted to serving and protecting our communities. To read Sheriff Binder’s full bio, click here.

Serving Our Community With Pride

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SO Employees

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Residents
*according to the latest U.S. Census Bureau data

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Calls for service in year 2025
*including all Bureaus of the Sheriff’s Office

Our mission is to protect and serve our communities by delivering professional policing and correctional services while upholding our commitment to public safety, community engagement, and organizational excellence.

About Us

Also in this section

Office History

San Mateo County Sheriff's Office

Sheriff John W. Ackerson

San Mateo Courthouse

Sheriff Silas Hovius

Sheriff Thomas W. Lathrop

Sheriff James McGrath

Modern Law Enforcement with Sheriff Earl B. Whitmore

Sub-stations at Mills Field

Crash Wagons

Crime Lab

Narcotics

Work Furlough Program

Sheriff Whitmore Retires

Sheriff John R. McDonald

Special Election

Sheriff Brendan Maguire

Sheriff Don Horsley

Sheriff Greg Munks

Sheriff Carlos G. Bolanos

Sheriff Christina Corpus

Sheriff Kenneth Binder

Serving Our Community With Pride

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San Mateo County Sheriff’s Office

San Mateo County Sheriff’s Office

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