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.
Thief River Falls, Minnesota, in Pennington County, has about 8,800 residents (2024 Census Bureau estimate). A person kept in custody after an arrest in Thief River Falls is held at the county jail, run by the Pennington 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: Thief River Falls public records, Pennington County inmate search, Thief River Falls arrest records, Thief River Falls warrants, Thief River Falls criminal records, Thief River Falls court records, Minnesota arrest records and Minnesota inmate search.
Finding Someone in Custody in Thief River Falls
A person kept in custody after an arrest in Thief River Falls is held at the county jail, run by the Pennington County Sheriff's Office, whichever agency made the arrest.
SearchSystems opened and checked the custody page of the Pennington County Sheriff's Office at incustodysearch.penningtonsheriff.org/ResponsiveInCustody.aspx (page title: In-Custody Search | Pennington County Sheriff's Office), which answered when SearchSystems opened it on September 23, 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 Pennington County Jail by the Numbers
On an average day in 2021 the jail held about 40 people, down from about 53 in 2019. Its rated capacity in 2019, the last year with a capacity figure, was 92 beds, and it ran at 58 percent of it that year. The figures are from the Vera Institute of Justice's Incarceration Trends data.
Pennington County has about 14,000 residents (2024 Census Bureau estimate), so the jail holds about 29 people for every 10,000 residents.
Who Books People Into the Pennington County Jail
The Pennington County Sheriff's Office and the agency that reports for Thief River Falls (filed by the FBI as Thief River Falls Police Department) make the arrests that end in a booking in and around Thief River Falls.
The FBI's agency list also places one more agency in Pennington County: the State Patrol at Thief River Falls (state police).
The largest arrest counts reported to the FBI were Thief River Falls's 138 for 2025 and the Pennington County Sheriff's Office's 33 for 2025.
Together, the two agencies in Pennington County with all twelve months of 2025 on file reported 171 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 Thief River Falls arrest records.
Frequently Asked Questions
How do I find an inmate in Thief River Falls?
Look on the custody page of the Pennington County Sheriff's Office at incustodysearch.penningtonsheriff.org. It covers people booked into the county jail.
How many people are in the Pennington County jail?
About 40 on an average day in 2021, the latest year in the Vera Institute's jail data, against a rated capacity of 92 beds.
Is this the official Thief River Falls website?
No. SearchSystems.net is an independent public records guide, online since 1997. It links to the official city, county, court and state offices described above and does not hold records, charge for them or take requests.