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.
Mercer County, Illinois, has about 15,000 residents (2024 Census Bureau estimate), and arrests there are reported to the FBI by the Mercer County Sheriff's Office and three city agencies. An arrest leaves the same records whoever makes it: the arresting agency's report, the record of anyone held at the county jail, and, if the State's Attorney files charges, a case in the Circuit Court of Mercer County. This guide says who keeps each one, what it costs and who may see it, with the arrest counts each agency reported.
This guide covers who makes arrests, how many arrests, booking and the jail, finding an arrest, copies, cities and common questions.
Related guides: Mercer County public records, Illinois arrest records, Illinois inmate search and Illinois criminal records.
Who Makes Arrests in Mercer County
The Mercer County Sheriff's Office is the county agency that reports arrests to the FBI for Mercer County. It reported 0 arrests for 2020, its latest complete year.
The FBI lists two cities in Mercer County with a reporting agency of their own, with the Census population and what each reported:
- Aledo, 3,522 residents: 11 arrests reported for 2025.
- Viola, 843 residents: 0 arrests reported for 2020.
A city on that list is reported separately whether the officers are the city's own or the sheriff's under contract; the FBI's list does not say which.
The Alexis Police Department is listed by the FBI across two counties including Mercer County, so its arrests are not broken out for Mercer County here.
How Many Arrests Aledo Reports
Each agency reports its arrests to the FBI by month, and the FBI publishes them on the Crime Data Explorer. These are the full-year totals, all offenses, as the FBI held them on October 8, 2026; a year with months missing or not reported is left out.
- Aledo: 11 for 2025, 34 for 2024, 37 for 2023, 40 for 2022, 59 for 2021 and 19 for 2020.
- Viola: 0 for 2020 and 0 for 2019.
- Mercer County Sheriff's Office: 0 for 2020.
Booking: Where People Arrested in Mercer County Are Held
A person kept in custody after an arrest in Mercer County is held at the county jail, whichever agency made the arrest, apart from the short stay some city departments' own holding cells allow; a person cited and released at the scene is not booked at all. The jail's record of each person held, with the charges, is a public record of the arrest, and the court file takes over from there.
On an average day in 2019 the jail held about 59 people. Its rated capacity in 2019 was 67 beds, and it ran at 88 percent of it that year. The figures are from the Vera Institute of Justice's Incarceration Trends data.
SearchSystems opened and checked the jail page of the Mercer County Sheriff's Office at mercercosheriff.org (page title: Mercer County Sheriff, IL), phone (309) 582-5194, 906 SW 3rd St. Aledo, IL 61231, which answered when SearchSystems opened it on September 23, 2026.
A sentence of more than a year is served in state prison; the Illinois Department of Corrections lists its inmates at idoc.illinois.gov/offender/inmatesearch.html.
How to Find Out About an Arrest in Mercer County
An arrest in Mercer County can be traced in two places, depending on where the case stands: the case index of the Circuit Court of Mercer County, kept by the Circuit Clerk, which shows whether charges were filed and the next court date; the State's Attorney, which decides whether an arrest becomes a charge (its page is at mercercountyil.org/deparments/states_attorney.php, phone (309) 582-5381).
The court records page SearchSystems verified for the county, at illinoiscourts.gov/courts-directory/104/Mercer-County-Courthouse/court (page title: Mercer County Court | State of Illinois Office of the Illinois Courts), phone (309) 582-7122, belongs to a lower court, not to the Circuit Court of Mercer County.
Illinois is one of the states that lets anyone look up another person's statewide criminal history: conviction information is public under the Uniform Conviction Information Act, through the Illinois State Police. That record shows what agencies reported to the state, which is wider than one county's court index but can lag it.
Getting a Copy of an Arrest Record in Mercer County
An arrest report belongs to the agency whose officer wrote it, and that agency releases it, not the court or the jail. Under the Illinois Freedom of Information Act the agency must answer within 5 business days, with one 5-day extension, and it may charge copying only after the first 50 pages.
- An arrest by the Mercer County Sheriff's Office: ask its records unit, reached through the office at (309) 582-5194.
- An arrest in Aledo or Viola: the records unit of the agency that reports for that city.
- A defendant who has been charged gets the report through the case: the State's Attorney, (309) 582-5381, handles discovery for pending cases.
- The court file of a case that was filed: in the Circuit Court of Mercer County it is kept by the Circuit Clerk. The court records page SearchSystems verified for the county, at illinoiscourts.gov, phone (309) 582-7122, is a lower court's.
- Any county record that is not posted: the county records request page SearchSystems verified is at mercercosheriff.org/foia/index.php (page title: Mercer County Sheriff, IL).
- Your own statewide record: a name-based or fingerprint-based request to the Illinois State Police.
Cities in Mercer County: Who Reports the Arrests
The FBI lists a separate arrest reporting agency for two of the nine cities in Mercer County: Aledo and Viola. Matherville, Sherrard, New Boston, Keithsburg, Joy, Seaton and North Henderson have no separate reporting agency in the FBI's list. The FBI's list also carries the New Windsor Police Department as a city agency in Mercer County; New Windsor is not among the cities above.
Wherever in the county the arrest happens, a person kept in custody goes to the county jail and the case goes to the Circuit Court of Mercer County.
Frequently Asked Questions
How many arrests are made in Mercer County each year?
Aledo reported 11 arrests to the FBI for 2025.
How do I find out if someone is in jail in Mercer County?
Ask the Mercer County Sheriff's Office at (309) 582-5194; its jail page SearchSystems verified is at mercercosheriff.org.
Where are people arrested in Mercer County booked?
Those kept in custody go to the county jail, run by the Mercer County Sheriff's Office; a person cited and released at the scene is not booked.
Are arrest records public in Mercer County?
The court files of criminal cases are public, and so is the statewide criminal history kept by the Illinois State Police: conviction information is public under the Uniform Conviction Information Act. The arrest report itself is released by the agency that made the arrest, under the Illinois Freedom of Information Act.
How do I get a copy of an arrest report in Mercer County?
From the agency that made the arrest: the Mercer County Sheriff's Office for its own arrests, or the agency that reports for the city where it happened. Under the Illinois Freedom of Information Act the answer is due within 5 business days, with one 5-day extension; the county records request page SearchSystems verified is at mercercosheriff.org/foia/index.php.
Is this the official Mercer 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.