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 23, 2026.
Rock Island County, Illinois, has about 143,000 residents (2024 Census Bureau estimate). A person kept in custody after an arrest in Rock Island County is held at the county jail, run by the Rock Island 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: Rock Island County public records, Rock Island County arrest records, Rock Island County warrants, Rock Island County police reports, Rock Island County property records, Illinois arrest records and Illinois inmate search.
Finding Someone in Custody in Rock Island County
The county jail, run by the Rock Island County Sheriff's Office, holds everyone kept in custody after an arrest in Rock Island County, from every agency.
SearchSystems opened and checked the jail page of the Rock Island County Sheriff's Office at rockislandcountyil.gov/318/Sheriffs-Office (page title: Sheriff's Office | Rock Island County, IL), phone 309-558-3432, 1317 Third Avenue County Justice Center Rock Island, IL 61201, Monday through Friday 8 am to 4:30 pm, 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 309-558-3432.
The Rock Island County Jail by the Numbers
On an average day in 2023 the jail held about 190 people, down from about 270 in 2019. Its rated capacity in 2023 was 329 beds, and it ran at 57 percent of it that year. The figures are from the Vera Institute of Justice's Incarceration Trends data.
Rock Island County has about 143,000 residents (2024 Census Bureau estimate), so the jail holds about 13 people for every 10,000 residents.
Who Books People Into the Rock Island County Jail
The Rock Island County Sheriff's Office and the agencies that report for Moline, Rock Island, East Moline, Silvis, Milan, Coal Valley and one more cities make the arrests that end in a booking in Rock Island County.
The FBI's agency list also places one more agency in Rock Island County: Black Hawk College at Moline (campus police).
The largest arrest counts reported to the FBI were Rock Island's 1,090 for 2025, Moline's 911 for 2025 and East Moline's 494 for 2025.
Together, the seven agencies in Rock Island County with all twelve months of 2025 on file reported 3,019 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 Rock Island 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 Rock Island County?
Ask the Rock Island County Sheriff's Office at 309-558-3432; its jail page SearchSystems verified is at rockislandcountyil.gov/318/Sheriffs-Office.
How many people are in the Rock Island County jail?
About 190 on an average day in 2023, the latest year in the Vera Institute's jail data, against a rated capacity of 329 beds.
What is the phone number for the Rock Island County jail?
309-558-3432, the number on the page of the Rock Island County Sheriff's Office SearchSystems verified.
Where do people sentenced to prison in Rock Island 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 Rock Island 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.