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 9, 2026.
St. Mary's County, Maryland, has about 116,000 residents (2024 Census Bureau estimate). A person kept in custody after an arrest in St. Mary's County is held at the county jail, run by the St. Mary's 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 and common questions.
Related guides: St. Mary's County public records, St. Mary's County arrest records, St. Mary's County warrants, St. Mary's County criminal records, St. Mary's County court records, Maryland arrest records and Maryland inmate search.
Finding Someone in Custody in St. Mary's County
A person kept in custody after an arrest in St. Mary's County is held at the county jail, run by the St. Mary's County Sheriff's Office, whichever agency made the arrest.
SearchSystems opened and checked the jail page of the St. Mary's County Sheriff's Office at publicportal.stmaryscountymd.gov (page title: St. Mary's County Sheriff's Office Public Portal), which answered when SearchSystems opened it on October 9, 2026.
That page is the office's jail information page rather than a roster.
The St. Mary's County Jail by the Numbers
On an average day in 2024 the jail held about 210 people, up from about 210 in 2019. Its rated capacity in 2019, the last year with a capacity figure, was 239 beds, and it ran at 87 percent of it that year. The figures are from the Vera Institute of Justice's Incarceration Trends data.
St. Mary's County has about 116,000 residents (2024 Census Bureau estimate), so the jail holds about 18 people for every 10,000 residents.
Who Books People Into the St. Mary's County Jail
The St. Mary's County Sheriff's Office makes the arrests that end in a booking in St. Mary's County.
The FBI's agency list also places these agencies in St. Mary's County: the St. Mary's County State Police (state police); St. Mary's College (campus police).
The St. Mary's County Sheriff's Office reported 1,792 arrests to the FBI for 2025. 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 St. Mary's County arrest records.
Frequently Asked Questions
How do I find an inmate in St. Mary's County?
Ask the St. Mary's County Sheriff's Office; its jail page SearchSystems verified is at publicportal.stmaryscountymd.gov.
How many people are in the St. Mary's County jail?
About 210 on an average day in 2024, the latest year in the Vera Institute's jail data, against a rated capacity of 239 beds.
Is this the official St. Mary's 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.