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 on September 24, 2026.
Fergus County, Montana, has about 12,000 residents (2024 Census Bureau estimate). A person kept in custody after an arrest in Fergus County is held at the county jail, run by the Fergus 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: Fergus County public records, Fergus County arrest records, Fergus County warrants, Fergus County criminal records, Fergus County court records, Montana arrest records and Montana inmate search.
Finding Someone in Custody in Fergus County
A person kept in custody after an arrest in Fergus County is held at the county jail, run by the Fergus County Sheriff's Office, whichever agency made the arrest.
SearchSystems opened and checked the custody page of the Fergus County Sheriff's Office at fergusmt.gov/detention-center-roster (page title: Fergus County, Montana | Detention Center Roster), phone (406) 535-3415, 712 W Main St, Lewistown, MT 59457, Mon - Fri, 8:00am - 5:00pm, which answered when SearchSystems opened it on September 24, 2026.
Someone booked recently shows on that page; someone cited and released at the scene, or held a few hours at a city station, does not.
The Fergus County Jail by the Numbers
On an average day in 2019 the jail held about 11 people. Its rated capacity in 2019 was 30 beds, and it ran at 38 percent of it that year. The figures are from the Vera Institute of Justice's Incarceration Trends data.
Fergus County has about 12,000 residents (2024 Census Bureau estimate), so the jail holds about 10 people for every 10,000 residents.
Who Books People Into the Fergus County Jail
The Fergus County Sheriff's Office and the agency that reports for Lewistown make the arrests that end in a booking in Fergus County.
The largest arrest counts reported to the FBI were Lewistown's 189 for 2025 and the Fergus County Sheriff's Office's 19 for 2025.
Together, the two agencies in Fergus County with all twelve months of 2025 on file reported 208 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 Fergus 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 Fergus County serves the sentence in a facility of the Montana Department of Corrections, whose inmate locator is at offendersearch.mt.gov/conweb.
Frequently Asked Questions
How do I find an inmate in Fergus County?
Look on the custody page of the Fergus County Sheriff's Office at fergusmt.gov/detention-center-roster, or call (406) 535-3415. It covers people booked into the county jail.
How many people are in the Fergus County jail?
About 11 on an average day in 2019, the latest year in the Vera Institute's jail data, against a rated capacity of 30 beds.
What is the phone number for the Fergus County jail?
(406) 535-3415, the number on the page of the Fergus County Sheriff's Office SearchSystems verified.
Where do people sentenced to prison in Fergus County go?
To a facility of the Montana Department of Corrections; its inmate locator is at offendersearch.mt.gov/conweb.
Is this the official Fergus 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.