Bail.com: Directory bail bondsmen, investigators, and defense attorneys, searchable by state.
DetectiveHelp.com: Searchable database of private investigators in the United States and Canada.
ExpertLaw: Find a private investigator or related service, by specialty and location.
ExpertPages.com: Investigative service providers, organized by specialty.
FindPiS.com: Directory of private investigators searchable by zip code.
Infoguys: International directory of private investigators.
International-Directories.com: International directory of private investigators and related products.
National Association of Fraud Investigators: Database of investigators focusing on Fraud Investigation.
National Association of Investigative Specialists: Membership directory, searchable by location and specialization.
Oklahoma Private Investigators Association: Offering a statewide directory of investigators.
PI Register.Com: International directory of private investigators.
PI Resources and Locator: Directory of private investigators with industry resources.
PIengine.com: International directory of investigators, organized geographically.
Pimall.com: Directory of private investigators with resources for this profession.
The Investigator Directory: Directory of investigators, process servers, and legal support service providers.