Williamson County Inmate Population Overview
The Williamson County inmate population is split between local and federal custody. The local side is the Williamson County Jail, operated by the Williamson County Sheriff's Office in Marion. It is the first place to check for a person arrested by the sheriff, a local police department, Illinois State Police, or another local agency when the person is held for booking, pretrial detention, a local sentence, or transfer paperwork. The sheriff's official pages identify the current jail and sheriff's office as the county facility used for local detention.
FCI Marion is different. It is a Federal Bureau of Prisons facility physically located in Williamson County, but it is not part of the county jail roster, county bond process, or Williamson County Circuit Clerk docket. A person at FCI Marion is searched through the BOP locator, not through the sheriff. No Illinois Department of Corrections prison was confirmed in Williamson County, but IDOC still matters after a local case ends in a state prison sentence.
Williamson County Inmate Population Statistics
The best detailed county jail count in the research is the 2018 Illinois Department of Corrections jail inspection. That report listed Williamson County Jail with a formal rated capacity of 240 beds, split between 218 male beds and 22 female beds. On the inspection day, July 17, 2018, the jail held 88 people. That is a point-in-time inspection count, not an average daily population and not a current roster total.
The federal number is current in a different way. The BOP public facility endpoint for FCI Marion reported 1,203 total people on June 4, 2026, with 997 at the main FCI and 206 at the camp. That number should not be merged into a county jail population figure. It shows why a broad Williamson County inmate population search can involve more than one custody system.
| Measure | Figure | Source / Date |
|---|---|---|
| Williamson County Jail rated capacity | 240 total beds | IDOC jail inspection, July 17, 2018 |
| Male and female bed split | 218 male, 22 female | IDOC jail inspection, 2018 |
| Inspection-day jail population | 88 total, 82 male, 6 female | IDOC jail inspection, July 17, 2018 |
| Cell and dorm layout | 96 double cells, two 24-person dorms | IDOC jail inspection, 2018 |
| FCI Marion population | 1,203 total | BOP public endpoint, June 4, 2026 |
Williamson County Jail Population Trends
Williamson County does not publish a current online jail population dashboard in the official county and sheriff sources reviewed. The sheriff's jail inspection page shows that annual IDOC inspections are part of local oversight, and the research located later inspection report links, but only the 2018 report supplied a detailed extracted population table. The current daily count, annual bookings, average length of stay, and demographic dashboard were not found in official public sources.
That gap is important. A single inspection-day count can show the facility's status on one day, but it cannot prove a trend by itself. The BOP number for FCI Marion is also not a trend point for the county jail because it is a separate federal prison count. A careful Williamson County inmate population review labels each number by facility, source, and date.
| Date | Population Figure | Use Note |
|---|---|---|
| July 17, 2018 | 88 at Williamson County Jail | County jail inspection-day count |
| October 15, 2020 | Not extracted | IDOC inspection date listed by sheriff page |
| June 30, 2021 | Not extracted | IDOC inspection date listed by sheriff page |
| June 4, 2026 | 1,203 at FCI Marion | Federal BOP facility count, not county jail count |
Who Is in Williamson County Custody
The county jail holds adults in local custody. The research describes pretrial detainees, local sentenced detainees, people awaiting transfer, and adults separated by male and female housing capacity. The 2018 IDOC inspection listed zero juvenile capacity and zero juveniles held on inspection day. It also described required jail records, classification, admission screening, property records, visitor records, and a master population locator or computer printout used inside the control center.
FCI Marion holds male federal inmates. The BOP source identifies the main institution as medium security and the satellite camp as minimum security. That federal population is part of the physical detention map in Williamson County, but it is not part of the sheriff's jail population. IDOC covers state-sentenced prisoners after transfer from county jail, and ICE covers immigration detention if a person moves into federal immigration custody.
- County jail custody: local arrest bookings, pretrial detainees, local sentences, holds, and transfer cases.
- State prison custody: Illinois sentenced prisoners after transfer to IDOC.
- Federal prison custody: BOP inmates at FCI Marion and its camp.
- Immigration custody: ICE detainees searched through the federal ODLS system.
Williamson County Inmate Population Laws
Illinois law frames how jail records, arrest reports, and jail oversight work. 5 ILCS 140, the Illinois Freedom of Information Act, gives public access to public records unless an exemption applies. The county FOIA page describes a standard five-working-day response for written requests and separate timing for commercial-purpose requests. The sheriff's FOIA page says fulfilled requests can be mailed, emailed, or picked up in the sheriff's lobby during normal business hours.
Key access rules: 5 ILCS 140/2.15 governs arrest-report access and certain booking-photo publication limits. 730 ILCS 5/3-15-2 gives IDOC county jail standards and inspection authority. 20 Ill. Admin. Code Part 701 sets county jail rules for administration, records, admission, release, classification, supervision, security, and related operations.
Those rules do not require Williamson County to place a live jail roster on the web. They do support record requests and inspection access, subject to exemptions for privacy, juvenile matters, active investigations, safety, protected victims or witnesses, and other limits. For the Williamson County inmate population, the practical result is a records path rather than a single public roster page.
Search the Williamson County Inmate Population
No official Williamson County Jail public web roster, current-inmates page, recent-bookings list, or sheriff inmate search portal was located on the county or sheriff site during research. The sheriff site has corrections, visitation, jail rules, PREA, inspection reports, jail history, records, civil process, and FOIA material. It did not expose an official online roster. That changes the search order: start with the sheriff and jail, then move to records requests, VINE, court records, IDOC, BOP, or ICE based on custody type.
- Gather the person's full legal name, spelling variants, date of birth or age, approximate arrest date, and arresting agency if known.
- Call the Williamson County Sheriff's Office at 618-997-6541 and ask whether public custody information is available by phone.
- If a record copy is needed, use the sheriff FOIA process for booking records, booking sheets, arrest reports, or booking photos.
- Check Illinois VINE for custody status and notification where available.
- Use IDOC Individual in Custody Search for a person sentenced to Illinois prison.
- Use the BOP Federal Inmate Locator for federal inmates, including FCI Marion.
Williamson County Roster Search Fields
Because no official Williamson County Jail web roster was located, there is no verified county search form with public fields such as last name, booking number, housing unit, charge, or booking date. The county search field table is therefore short by design. It is more accurate to say the official online roster field list is unavailable than to borrow fields from another county or from unofficial aggregator sites.
| Field Label | Type | Required | Notes |
|---|---|---|---|
| Not available | n/a | n/a | No official Williamson County Jail web roster or search form was found. |
For federal inmates, the BOP name locator does publish a form. It includes first name, middle name, last name, race options, sex options, and age. A BOP register number search is often stronger when known, but many local searches start with a name.
Williamson County Inmate Record Contents
The public web profile fields for a Williamson County Jail inmate cannot be listed because no official online profile was found. The 2018 IDOC inspection still confirms that the jail maintains core internal records. It asks whether booking and personal records are maintained for each detainee, whether fingerprints and photographs are taken under current law, whether property is receipted, and whether case disposition, judge, court, visitor, medical, discipline, and housing locator records are maintained.
| Record Item | What It Shows |
|---|---|
| Booking and personal record | Core jail intake and identity record for each detainee. |
| Fingerprints and photograph | Admission identification steps required by inspection standards. |
| Property receipt | Items taken from the detainee and signatures tied to custody of property. |
| Medical screening | Health, medication, mental-health, injury, pregnancy, and self-harm screening notes. |
| Visitor record | Visitor names and visit dates kept in the detainee file. |
| Master population locator | Internal housing sections and assignments at the control center. |
County Jail vs State Prison
A Williamson County jail booking and an IDOC prison record answer different questions. The jail record is about local custody after arrest, intake, release, transfer, or a short local sentence. The IDOC locator is for sentenced Illinois prisoners after they leave county jail. Court records stay with the Williamson County Circuit Clerk and Judici even when the person later transfers to prison.
| Question | County Jail | IDOC or BOP |
|---|---|---|
| Who runs it? | Williamson County Sheriff's Office | Illinois DOC or Federal BOP |
| Who is covered? | Local arrests, pretrial custody, local sentences | State or federal sentenced inmates |
| Best lookup channel | Sheriff phone, FOIA, VINE, court records | IDOC locator or BOP locator |
| What it does not show | Federal prison location or state sentence details | County booking photo, local bond status, jail housing |
Williamson County Detention Facilities
The facility map for Williamson County has two confirmed pages. The Williamson County Jail is the local custody facility. FCI Marion is the federal prison in the county. No separate official city jail, regional jail, ICE detention facility, or IDOC state prison in Williamson County was confirmed from official sources.
- Williamson County Jail - county jail for local adult bookings, pretrial detention, local sentenced detainees, and transfer cases.
- FCI Marion - medium-security federal correctional institution with a minimum-security satellite camp for male federal inmates.
The sheriff also has an official iOS app listing and Google Play listing. The store text describes tips, crime reporting, interactive features, and public safety news. It did not confirm an app-only inmate roster or mugshot feature.
Williamson County Inmate Population FAQ
How big is the Williamson County inmate population? The county jail's detailed official count in the research is the 2018 IDOC inspection-day population of 88 people against 240 rated beds. FCI Marion, a separate federal facility in the county, reported 1,203 people on June 4, 2026.
Is there a Williamson County jail roster online? No official public web roster was located on the sheriff or county sites. Use the sheriff phone line, in-person contact, sheriff FOIA, VINE, Judici, IDOC, BOP, or ICE based on custody type.
Can released inmate records be found? Released local custody records may require a sheriff FOIA request for a booking sheet, arrest report, release or transfer record, or booking photo. Filed charges are searched through the Circuit Clerk and Judici.
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