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.
Lake County, Illinois, has about 719,000 residents (2024 Census Bureau estimate). A person kept in custody after an arrest in Lake County is held at the county jail, run by the Lake 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: Lake County public records, Lake County arrest records, Lake County warrants, Lake County criminal records, Lake County court records, Illinois arrest records and Illinois inmate search.
Finding Someone in Custody in Lake County
A person kept in custody after an arrest in Lake County is held at the county jail, run by the Lake County Sheriff's Office, whichever agency made the arrest.
SearchSystems opened and checked the custody page of the Lake County Sheriff's Office at lakecountyil.gov/2031/Inmate-Information (page title: Inmate Information | Lake County, IL), 29 S Martin Luther King Jr Avenue, Waukegan, IL 60085, a site that blocks automated checks (HTTP 429), so open it in a browser.
That page is the place to look for someone booked recently. A person cited and released at the scene, or held only a few hours by a city department, will not be on it.
The Lake County Jail by the Numbers
On an average day in 2024 the jail held about 510 people, down from about 630 in 2019. Its rated capacity in 2019, the last year with a capacity figure, was 740 beds, and it ran at 85 percent of it that year. The figures are from the Vera Institute of Justice's Incarceration Trends data.
Lake County has about 719,000 residents (2024 Census Bureau estimate), so the jail holds about 7 people for every 10,000 residents.
Who Books People Into the Lake County Jail
The Lake County Sheriff's Office and the agencies that report for Waukegan, Buffalo Grove, Mundelein, Highland Park, North Chicago, Gurnee and 27 more cities make the arrests that end in a booking in Lake County.
The FBI's agency list also places one campus police department and three other agencies in Lake County (the arrest records guide names each one).
The Barrington Police Department, the Island Lake Police Department, the Fox River Grove Police Department and one more are each listed by the FBI across several counties including Lake County, so their arrests are not broken out for Lake County here.
The largest arrest counts reported to the FBI were Waukegan's 1,366 for 2025, Mundelein's 668 for 2025 and the Lake County Sheriff's Office's 656 for 2025.
Together, the 31 agencies in Lake County with all twelve months of 2025 on file reported 7,816 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 Lake 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 Lake County?
Look on the custody page of the Lake County Sheriff's Office at lakecountyil.gov/2031/Inmate-Information. It covers people booked into the county jail.
How many people are in the Lake County jail?
About 510 on an average day in 2024, the latest year in the Vera Institute's jail data, against a rated capacity of 740 beds.
Where do people sentenced to prison in Lake 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 Lake 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.