Reviewed and updated October 7, 2026 by the SearchSystems.net editorial team. 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.
Cook County, Illinois, has about 5.2 million residents (2024 Census Bureau estimate), and arrests there are reported to the FBI by the Cook County Sheriff's Office, 118 city agencies and 29 campus, state or other agencies. An arrest leaves the same records whoever makes it: the arresting agency's report, the booking at the county jail, and, if the State's Attorney files charges, a case in the Circuit Court of Cook County. This guide says who keeps each one, what it costs and who may see it.
This guide covers who makes arrests, booking and the jail, finding an arrest, copies, cities and common questions.
Related guides: Cook County public records, Illinois arrest records, Illinois inmate search and Illinois criminal records.
Who Makes Arrests in Cook County
The Cook County Sheriff's Office is the county agency that reports arrests to the FBI for Cook County.
The FBI lists 118 cities in Cook County with a reporting agency of their own, with the Census population and what each reported, the largest twelve first; the rest are in the cities section below:
- Chicago, 2,721,308 residents.
- Cicero, 82,090 residents.
- Schaumburg, 77,099 residents.
- Evanston, 76,006 residents.
- Arlington Heights, 75,596 residents.
- Palatine, 65,951 residents.
- Skokie, 65,850 residents.
- Des Plaines, 58,832 residents.
- Orland Park, 58,020 residents.
- Oak Lawn, 56,531 residents.
- Mount Prospect, 55,460 residents.
- Berwyn, 55,152 residents.
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 FBI's agency list also places these agencies in Cook County: University of Illinois: Chicago, Chicago State University, Northeastern Illinois University and Oakton Community College and ten more (campus police); Canadian Pacific Railway, Metra Police Department, Chicago Heights Park District and Chicago Fire Department Arson Investigations and 11 more (other).
Booking: Where People Arrested in Cook County Are Held
A person held after an arrest in Cook County is booked into the county jail, whichever agency made the arrest. The booking record, with the charges, is the first public record of the arrest; once the person is released or sentenced the record continues in the court file.
On an average day in 2024 the jail held about 4,790 people, down from about 5,770 in 2019. Its rated capacity in 2023, the last year with a capacity figure, was 7,084 beds, and it ran at 73 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 Cook County Sheriff's Office at cookcountyil.gov/service/locate-inmate (page title: Locate an Inmate), 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 Cook County
An arrest in Cook County can be traced in two places, depending on where the case stands: the case index of the Circuit Court of Cook County, which shows whether charges were filed and the next court date (the court records page SearchSystems verified is at cookcountyil.gov/service/court-records-and-archives); the State's Attorney, which decides whether an arrest becomes a charge (its page is at cookcountyil.gov/agency/states-attorney, phone (312) 603-1880).
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 Cook 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 Cook County Sheriff's Office: ask its records unit.
- An arrest in Chicago, Cicero, Schaumburg, Evanston, Arlington Heights or Palatine or another of the cities listed above: the records unit of the agency that reports for that city; the city guides linked above name each city's records office.
- An arrest by University of Illinois: Chicago, Chicago State University or Northeastern Illinois University: that agency's own records office.
- A defendant who has been charged gets the report through the case: the State's Attorney, (312) 603-1880, handles discovery for pending cases.
- The court file of a case that was filed: the Circuit Court of Cook County, through its records page at cookcountyil.gov.
- Your own statewide record: a name-based or fingerprint-based request to the Illinois State Police.
Cities in Cook County: Who Reports the Arrests
The FBI lists a separate arrest reporting agency for 118 of the 119 cities in Cook County. Ford Heights has no separate reporting agency in the FBI's list.
Wherever in the county the arrest happens, the booking is at the county jail and the case goes to the Circuit Court of Cook County.
SearchSystems has a guide to the offices of these cities in Cook County, with the 2024 Census Bureau population:
- Chicago (2,721,308)
- Evanston (76,006)
- Arlington Heights (75,596)
- Palatine (65,951)
- Des Plaines (58,832)
- Orland Park (58,020)
- Oak Lawn (56,531)
- Mount Prospect (55,460)
- Berwyn (55,152)
- Tinley Park (54,856)
- Hoffman Estates (50,920)
- Park Ridge (38,445)
- Streamwood (38,360)
- Wheeling (38,329)
- Hanover Park (36,685)
- Calumet City (34,855)
- Northbrook (34,546)
- Niles (29,918)
- Burbank (28,606)
- Lansing (28,107)
- Wilmette (27,443)
- Oak Forest (26,813)
- Chicago Heights (26,533)
- Morton Grove (24,467)
- Elmwood Park (23,698)
- Blue Island (21,805)
- Park Forest (21,016)
- Dolton (20,697)
- Evergreen Park (19,301)
- Brookfield (18,885)
- Matteson (18,566)
- Alsip (18,486)
- Lemont (18,203)
- Bellwood (18,132)
- Franklin Park (18,110)
- Palos Hills (18,026)
- Bridgeview (16,559)
- Westchester (16,313)
- Country Club Hills (16,238)
- Prospect Heights (15,566)
Frequently Asked Questions
How do I find out if someone is in jail in Cook County?
Ask the Cook County Sheriff's Office; its jail page SearchSystems verified is at cookcountyil.gov/service/locate-inmate.
Where are people arrested in Cook County booked?
In the county jail, run by the Cook County Sheriff's Office.
Are arrest records public in Cook 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 Cook County?
From the agency that made the arrest: the Cook 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.
Is this the official Cook 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.