P.O. Box 22
Nashville, IL 62263
Phone: 618-327-9526
Toll free: 800-995-7717
Fax: 618-327-9070

Contact Us

Get a free consultation

Captcha Image

Site Map


Advanced Investigative Services is a full service investigative firm that offers comprehensive investigative services throughout the state of Illinois, as well as the greater St. Louis, MO area, and specialized investigative services throughout the states of Illinois, Indiana, Kansas, Kentucky, Missouri, and Tennessee.

About Us

Advanced Investigative Services, Incorporated has gained a reputation of being aggressive, but highly ethical, while producing exceptional results for our clients. We employ experienced, licensed investigators, who reside throughout the state of Illinois, and who also service the states of Illinois, Indiana, Kansas, Kentucky, Missouri, and Tennessee from these locations. We are capable of offering national and world wide investigative services or contacts through the professional organizations to which we belong.

Our Team

AIS was founded in 1996 by William R. Barrett, a retired Illinois State Police Captain, who has over 35 years of varied and complex investigative experience. The organization has rapidly grown to become the premier investigative agency in the Midwest by placing experienced, professional, and aggressive investigators throughout the area of coverage. The current staff consists of over 40 licensed investigators, who are primarily from investigative backgrounds at the local, state and federal levels.

Our Services



  • Attorney Services
  • Consulting
  • Workman Compensation
  • Video Surveillance
  • Undercover Operations
  • Pre-employment Screening
  • Background Checks
  • Insurance Fraud
  • Embezzlement/Theft
  • Asset Recovery/Searches
  • Process Service
  • Interviews/Statements
  • Product liability
  • Pre-trial Investigations
  • Crime Scene Investigations
  • Covert And Overt Camera Installation

Intellectual Property

  • Current Relationships With Numerous National Companies
  • Investigators Specifically Trained By National Companies
  • Experienced Investigators In The Service Of Cease And Desist Orders, Conducting Comprehensive Interviews, Receiving Surrendered Property Labeled To The National Manufacturer

Executive Protection Services

  • Experienced And Professional Staff Members
  • Surveillance Operations And Surveillance Detection
  • Lead Protection Specialist Has Over Twenty (20) Years Of Law Enforcement Experience
    • Currently Is A Special Agent For The U.S. Military Specializing In Protective Services
    • Has Significant Experience In Undercover Operations, Surveillance And Criminal Investigations
    • Protection Experience With High Level Executives And Government Officials Trained In:
      • Firearms
      • Defensive Tactics
      • Surveillance
      • Driving Tactics
      • Personal Protection By An Elite Training School


  • Domestic
  • Child Custody
  • Missing Persons
  • Pre-marital Background
  • Divorce
  • Stalking
  • Protective Services


  • Video/Still Photography
  • licensed Pilots
  • licensed Investigators
  • Surveillance Technician
  • Accident Reconstructionist
  • Criminal Defense Detectives
  • Crime Scene Expert
  • Ballistics Expert
  • Serologist
  • Polygraph Examiner
  • Audit/Fraud Expert
  • Covert/Overt Corporate Investigators
  • Fire Cause And Origin Specialist
  • Covert And Overt Camera Installation
  • Executive Protection Experts

Comprehensive Intelligence Databases Providing:

  • Locate Searches
  • Missing Persons
  • Driving Records, licenses, Etc.
  • Criminal History Records
  • Civil And Divorce Searches

Helpful Links

Illinois: 117-000899
Indiana: PI20700065
Kansas: A-5205
Kentucky: KYPI-0123
Missouri: 2010019307
Tennessee: 00001951
Illinois Security Agency License: 122-001103