Every month, thousands of divorced individuals write alimony checks they may no longer legally owe — simply because they cannot prove their ex-spouse is living with a new partner. For a full breakdown of what Illinois courts require to terminate spousal maintenance, read Illinois Alimony Laws and Cohabitation: What You Need to Prove in Court. Proving cohabitation used to require weeks of costly surveillance, stakeouts, and luck. Today, license plate recognition (LPR) technology has changed the game entirely.
At P.I. Radames, I use IRBsearch's nationwide LPR database as one of the most powerful tools in my investigative arsenal. Here is how it works — and how it recently helped a client in the Chicago area save thousands of dollars.
What Is LPR Technology?
License plate recognition technology uses high-speed cameras mounted on police vehicles, repossession trucks, parking enforcement units, and fixed infrastructure to automatically photograph and log license plates as vehicles pass by. Each scan captures the plate number, the GPS location, the date, and the exact time.
Over time, millions of these scans accumulate into a massive, searchable database. Through IRBsearch, licensed private investigators can query that database to see where a specific vehicle has been spotted — and when.
Think of it as a digital breadcrumb trail that a vehicle leaves behind every time it passes a camera-equipped vehicle or fixed reader, whether the driver knows it or not. It is also worth noting that attempting to place a physical GPS tracker yourself is a criminal offense in Illinois — read GPS Tracking Laws in Illinois before you consider any DIY approach.
What IRBsearch Adds to the Picture
IRBsearch is one of the most comprehensive investigative data platforms available to licensed PIs. Their LPR database aggregates scan data from a nationwide network of readers, giving investigators the ability to:
- Search by license plate number to see a vehicle's historical location hits
- Search by address to see which vehicles have been repeatedly spotted at a specific location
- Identify patterns — such as a vehicle appearing at the same address every night between 10 PM and 7 AM
- Cross-reference vehicle registrations to identify who owns the car parked at a subject's residence
This is not a one-time snapshot. It is a pattern of behavior documented over weeks or months — exactly the kind of evidence that holds up when presented to a family law attorney or a judge.
The Case: A Cohabitation Investigation in Cook County
The following is a representative case composite. Names and identifying details have been changed to protect client confidentiality.
A client — I will call him Marcus — had been paying $2,200 per month in alimony to his ex-wife for nearly three years. Under the terms of their divorce decree, those payments were to terminate if she began cohabiting with a romantic partner on a resident basis.
Marcus had strong suspicions. His ex-wife's social media showed photos with the same man repeatedly. Mutual friends mentioned she was "basically living with someone." But suspicion is not evidence, and his attorney needed documentation before filing a motion to terminate support.
Marcus came to me after a friend referred him. He was frustrated — he had already spent money on a traditional surveillance attempt that produced nothing conclusive. His ex-wife seemed to know when someone was watching.
Step One: Running the LPR Query
The first thing I did was run an IRBsearch LPR query on the address where Marcus believed the new partner lived. Within minutes, I had a report showing vehicle sightings at that address going back several months.
One vehicle stood out immediately — a late-model SUV registered to a man I will call Daniel. That vehicle had been scanned at the address 47 times over a 90-day period, with the majority of hits occurring between 9 PM and 8 AM. Several hits showed the vehicle present on consecutive days, including weekends and holidays.
I then ran a reverse query on Marcus's ex-wife's vehicle. Her car appeared at Daniel's address on 31 separate occasions during the same window — again, predominantly overnight.
Step Two: Corroborating the Data
LPR data is powerful, but I always corroborate it with additional documentation. I conducted a focused, two-day surveillance operation — not weeks of expensive stakeouts, but a targeted confirmation based on what the data already told me.
On the first night, I observed Marcus's ex-wife's vehicle arrive at Daniel's address at 9:47 PM. It was still present when I returned at 6:30 AM the following morning. On the second visit, I documented the same pattern and captured timestamped photographs of both vehicles in the driveway simultaneously.
The LPR data established the pattern. The surveillance confirmed it.
Step Three: Delivering the Evidence Package
I compiled a full evidence package for Marcus's attorney that included:
- The IRBsearch LPR report with all 47 vehicle sightings, dates, times, and GPS coordinates
- The reverse query showing his ex-wife's vehicle at Daniel's address
- Timestamped surveillance photographs from both observation sessions
- A written investigative summary suitable for use in court proceedings
The Outcome
Marcus's attorney filed a motion to terminate alimony based on cohabitation. Faced with the LPR data and photographic evidence, the opposing party did not contest the motion. The alimony obligation was terminated.
At $2,200 per month, Marcus was looking at potentially years of continued payments. The total cost of the investigation — including the LPR research and the two targeted surveillance sessions — was a fraction of what he would have paid in a single month of alimony.
Why LPR Changes the Economics of Cohabitation Cases
Traditional cohabitation surveillance is expensive because it is time-intensive. An investigator may spend 10, 20, or 30 hours watching a location before capturing meaningful evidence — and there is no guarantee the subject will cooperate by following a predictable schedule.
LPR data flips that equation. Instead of waiting for behavior to happen in real time, I can query months of historical data in minutes. That data tells me whether a pattern exists before I ever pick up a camera. If the data shows consistent overnight presence, I know exactly when and where to focus a targeted surveillance session to corroborate it.
The result is faster answers, lower costs, and stronger evidence.
Is LPR Evidence Admissible?
LPR data obtained through licensed investigative databases like IRBsearch is legally gathered from public roadways and parking areas. Vehicles on public roads have no reasonable expectation of privacy regarding their location. This data has been used successfully in family law proceedings, civil litigation, and criminal investigations across the country.
That said, every case is different. I always recommend working with a qualified family law attorney to understand how evidence will be presented and what standard of proof applies in your jurisdiction.
Could LPR Help Your Case?
If you are paying alimony and believe your ex-spouse may be cohabitating with a new partner, LPR technology may be able to answer that question faster and more affordably than you think.
I serve clients throughout the Chicago metropolitan area, including Cook, DuPage, Lake, and Will counties. Every consultation is completely confidential.
Reach out today to discuss your situation. The truth is out there — and with the right tools, it does not take long to find it.
