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 September 25, 2026.
Winnebago County, Illinois, has about 284,000 residents (2024 Census Bureau estimate). A person kept in custody after an arrest in Winnebago County is held at the county jail, run by the Winnebago 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: Winnebago County public records, Winnebago County arrest records, Winnebago County warrants, Winnebago County criminal records, Winnebago County court records, Illinois arrest records and Illinois inmate search.
Finding Someone in Custody in Winnebago County
The county jail, run by the Winnebago County Sheriff's Office, holds everyone kept in custody after an arrest in Winnebago County, from every agency.
SearchSystems opened and checked the jail page of the Winnebago County Sheriff's Office at inmates.winnebagosheriff.com (page title: Winnebago County Sheriff's Office -- Inmate Inquiry), which answered when SearchSystems opened it on September 25, 2026.
That page is the office's jail information page rather than a roster.
The Winnebago County Jail by the Numbers
On an average day in 2024 the jail held about 730 people, down from about 810 in 2019. Its rated capacity in 2023, the last year with a capacity figure, was 1,324 beds, and it ran at 58 percent of it that year. The figures are from the Vera Institute of Justice's Incarceration Trends data.
Winnebago County has about 284,000 residents (2024 Census Bureau estimate), so the jail holds about 26 people for every 10,000 residents.
Who Books People Into the Winnebago County Jail
The Winnebago County Sheriff's Office and the agencies that report for Rockford, Loves Park, Machesney Park, Roscoe, South Beloit, Rockton and four more cities make the arrests that end in a booking in Winnebago County.
The FBI's agency list also places one campus police department and three other agencies in Winnebago County (the arrest records guide names each one).
The largest arrest counts reported to the FBI were Rockford's 4,728 for 2025, the Winnebago County Sheriff's Office's 1,921 for 2025 and Machesney Park's 636 for 2025.
Together, the 11 agencies in Winnebago County with all twelve months of 2025 on file reported 8,899 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 Winnebago County arrest records.
From the Jail to State Prison
A sentence of more than a year is served in state prison, not the jail; the Illinois Department of Corrections lists its inmates at idoc.illinois.gov/offender/inmatesearch.html.
Frequently Asked Questions
How do I find an inmate in Winnebago County?
Ask the Winnebago County Sheriff's Office; its jail page SearchSystems verified is at inmates.winnebagosheriff.com.
How many people are in the Winnebago County jail?
About 730 on an average day in 2024, the latest year in the Vera Institute's jail data, against a rated capacity of 1,324 beds.
Where do people sentenced to prison in Winnebago County go?
To a facility of the Illinois Department of Corrections; its inmate locator is at idoc.illinois.gov/offender/inmatesearch.html.
Is this the official Winnebago 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.