Northshore Process Service Network
“I used Northshore Process for skiptraces and to achieve service, and was very satisfied with their timely services!”
Best Private Investigators in Chicago, IL
24 agencies listed · all 24 in Chicago · 9 open 24/7 · 14 open weekends · 19 rated 4.5+
Data verified October 21, 2026
RA Private Investigation & Security
“I highly recommend RA for their outstanding service and meticulous approach to ensuring accurate information”
Lawdog Security & Investigations
“From what I have heard about LawDog from a police officer I know is they are very professional all in together a great company.”
Usia Private Security
“We've contracted with multiple companies over the years and USIA has provided the best services.”
PCI Investigations
“I would recommend it to anyone needing a PI whatever your case may be!”
Chicago Executive Protection - Secure Options Consulting
“Beyond their impressive credentials, their adaptability to our ever-evolving daily challenges, from having guards arrive ahead of schedule to staying late for unforeseen events, has been commendable.”
The 24 agencies on this page are the private investigators listed for Chicago, IL. What each one states about its license, its specialties and the areas it covers comes from its own website; ratings and quotes come from public reviews.
Area overview: Chicago, IL
All 24 agencies we list here are in Chicago itself. We have 30 agencies in Chicago on file; this page shows the highest-rated 24. 22 of the agencies on this page have a rating, from 4.0 to 5.0 across 314 reviews; 2 have 50 or more reviews and 19 are rated 4.5 or higher. 9 are open around the clock; 14 are open on Saturdays and 13 on Sundays. 13 show a license on their websites and 2 have a BBB rating of A or A+. Domain records put 19 websites of the agencies on this page at ten or more years old; the oldest dates from 1998. 9 offer urgent consultations and 9 offer a free initial consultation. We have a website on file for all 24 of the agencies on this page; 22 publish a contact page; 16 list a public email and 1 takes bookings online. We count these figures across the agencies on this page; hours and prices change, so confirm the details with the agency before you book.
Do investigators listed for Chicago discuss a case free?
9 of the 24 agencies state that a first consultation costs nothing. Use it to describe the problem and hear whether the work can be done lawfully at all. A straight agency will sometimes tell you on that call that what you want cannot be obtained, which saves you a retainer.
U.S. Security and Protective Services
“Very professional place well structured i recommend them for their services!!!!”
Citywide Security Group
International Protective Services
Key Chicago Private Investigators
“Jeanne was very thoughtful in her preliminary questioning and then did a great job setting up a strategic plan of action; with excellent follow-through and timely updates.”
Vantius
“Out of all the PIs I contacted in the Chicagoland area, Vantius made me feel the most comfortable and at ease with my situation.”
Myers Service
“I spoke to Nerdisa and she was knowledgeable and gracious in answering all of my questions and I had many.”
Heritage Investigations & Surveillance
“I have worked with Adam Campbell over the last 34 years on complex personal injury and criminal cases and have never been disappointed by the quality of service and integrity of him and his company.”
Chicago Private Investigator
“From interviewing witnesses to getting documents, police reports, medical records, (and anything else), Bob always comes through very quickly.”
Vander Weele Group
“I really think these people are the most caring, helpful and dedicated individuals!”
Ingenium Consulting Group
“Called Ingenium the took care of all the problems.”
Omega Global Security
Axium Consulting
Legal Eye
Todd Martinson
“Extremely competent, reliable and reasonably priced”
National Protection & Investigation Agency
Due Process Investigations
Subrosa Investigations
Localdetectives.com
Why these companies made our list
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