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.
Marengo, Illinois, in McHenry County, has about 7,700 residents (2024 Census Bureau estimate). A DUI arrest in Marengo starts two cases, a criminal case in the Circuit Court of McHenry County and a license case before the Secretary of State, and leaves three records. This guide follows the arrest from the roadside to the court file and the driving record.
This guide covers the law, the arrest, booking, the court case, the license case, the records and common questions.
Related guides: Marengo public records, McHenry County DUI, Marengo arrest records, Marengo warrants, Marengo inmate search, Marengo criminal records, Illinois arrest records and Illinois inmate search.
The DUI Law in Illinois
Drunk driving is charged as DUI in Illinois, at a blood alcohol level of 0.08 or more.
Driving in Illinois is consent to a breath or blood test when an officer has cause to suspect DUI; the license case that follows a refusal or a failed test is run by the Secretary of State, separately from the criminal case.
Illinois sets no time limit on prior offenses: every earlier conviction counts toward a repeat charge.
Who Makes DUI Arrests in Marengo
The McHenry County Sheriff's Office and the agency that reports for Marengo (filed by the FBI as Marengo Police Department) make the DUI arrests in and around Marengo.
The FBI's agency list also places these agencies in McHenry County: McHenry County College (campus police); the McHenry County Conservation District and the Crystal Lake Park District (other agency).
Together, the 21 agencies in McHenry County with all twelve months of 2025 on file reported 4,544 arrests to the FBI that year, all offenses together; the FBI's count for McHenry County does not break DUI out.
The Lakemoor Police Department, the Fox Lake Police Department and the Barrington Hills Police Department are each listed by the FBI across several counties including McHenry County, so their arrests are not broken out for McHenry County here.
Booking After a DUI Arrest in Marengo
A driver arrested for DUI and kept in custody goes to the county jail, whichever agency made the arrest. The jail, run by the McHenry County Sheriff's Office, held about 380 people on an average day in 2024 by the Vera Institute of Justice's count and has a jail page SearchSystems verified at mchenrysheriff.org. The Marengo inmate search guide covers the jail in full.
The Court Case
A DUI charge from Marengo is brought by the State's Attorney in the Circuit Court of McHenry County.
The State's Attorney's page SearchSystems verified is at mchenrycountyil.gov, phone (815) 334-4159.
The court records page SearchSystems verified for the county is at caseinfo.mchenrycountyil.gov/PublicCaseAccess.
Illinois has no single public index of every trial court case; each court's records are looked up through that court.
The License Case
The court case is only half the record. The Secretary of State runs a separate administrative case over the license, which can suspend it before the criminal case is decided, and the Illinois Secretary of State keeps the driving record the conviction goes on.
The Records a DUI Leaves
- The arrest report: from the agency that made the arrest, under the Illinois Freedom of Information Act.
- The court file: from the Circuit Court of McHenry County, kept by the Circuit Clerk.
- The driving record: from the Illinois Secretary of State.
More on each: Marengo arrest records and Marengo court records.
Frequently Asked Questions
What is the DUI limit in Illinois?
0.08 percent blood alcohol.
Where is a DUI case from Marengo heard?
In the Circuit Court of McHenry County, brought by the State's Attorney.
Where is a person arrested for DUI in Marengo held?
At the county jail, run by the McHenry County Sheriff's Office, if kept in custody.
Who handles the license after a DUI arrest in Illinois?
The Secretary of State, in an administrative case separate from the court case.
How long does a DUI count as a prior in Illinois?
There is no time limit; every prior conviction counts.
Is this the official Marengo website?
No. SearchSystems.net is an independent public records guide, online since 1997. It links to the official city, county, court and state offices described above and does not hold records, charge for them or take requests.