Reviewed and updated October 9, 2026 by the SearchSystems.net editorial team. The arrest counts are the ones each agency reported to the FBI, as the FBI held them on October 8, 2026. The jail figures are from the Vera Institute of Justice's Incarceration Trends data. Every office link was opened and checked against the office's own site between September 23, 2026 and October 2, 2026.
Marin County, California, has about 256,000 residents (2024 Census Bureau estimate). A person kept in custody after an arrest in Marin County is held at the county jail, run by the Marin County Sheriff's Office, and the jail's record of each person held is a public record. This guide says where to look for someone in custody, what the jail holds and who books people into it.
This guide covers the search, the jail, who books people, state prison and common questions.
Related guides: Marin County public records, Marin County arrest records, Marin County warrants, Marin County criminal records, Marin County court records, California arrest records and California inmate search.
Finding Someone in Custody in Marin County
A person kept in custody after an arrest in Marin County is held at the county jail, run by the Marin County Sheriff's Office, whichever agency made the arrest.
SearchSystems opened and checked the jail page of the Marin County Sheriff's Office at marinsheriff.gov/about-us/detention-bureau (page title: Detention Bureau | Marin County Sheriff), phone (415) 473-6653, which answered when SearchSystems opened it on September 23, 2026.
That page is the office's jail information page rather than a roster, so a search for a particular person goes through the office at (415) 473-6653.
The Marin County Jail by the Numbers
On an average day in 2025 the jail held about 260 people, down from about 280 in 2019. Its rated capacity in 2023, the last year with a capacity figure, was 386 beds, and it ran at 65 percent of it that year. The figures are from the Vera Institute of Justice's Incarceration Trends data.
Marin County has about 256,000 residents (2024 Census Bureau estimate), so the jail holds about 10 people for every 10,000 residents.
Who Books People Into the Marin County Jail
The Marin County Sheriff's Office and the agencies that report for San Rafael, Novato, Mill Valley, Tiburon, Fairfax, Sausalito and two more cities make the arrests that end in a booking in Marin County.
The FBI's agency list also places these agencies in Marin County: Union Pacific Railroad in Marin County (other agency); Marin Community College (campus police); the Highway Patrol's Marin Area Office (state police).
The largest arrest counts reported to the FBI were San Rafael's 1,661 for 2025, Novato's 1,018 for 2025 and the Marin County Sheriff's Office's 874 for 2023.
Together, the seven agencies in Marin County with all twelve months of 2025 on file reported 3,134 arrests to the FBI that year. Those kept in custody were booked into the county jail; a person cited and released at the scene was not.
The counts, agency by agency and year by year, are in Marin County arrest records.
From the Jail to State Prison
The jail holds people awaiting trial and people serving short sentences. A person sentenced to prison in Marin County serves the sentence in a facility of the California Department of Corrections and Rehabilitation, whose inmate locator is at cdcr.ca.gov/search.
Frequently Asked Questions
How do I find an inmate in Marin County?
Ask the Marin County Sheriff's Office at (415) 473-6653; its jail page SearchSystems verified is at marinsheriff.gov/about-us/detention-bureau.
How many people are in the Marin County jail?
About 260 on an average day in 2025, the latest year in the Vera Institute's jail data, against a rated capacity of 386 beds.
What is the phone number for the Marin County jail?
(415) 473-6653, the number on the page of the Marin County Sheriff's Office SearchSystems verified.
Where do people sentenced to prison in Marin County go?
To a facility of the California Department of Corrections and Rehabilitation; its inmate locator is at cdcr.ca.gov/search.
Is this the official Marin County website?
No. SearchSystems.net is an independent public records guide, online since 1997. It links to the official county, court and state offices described above and does not hold records, charge for them or take requests.