Updated: Sep 23, 2022
It is extremely important to hire a PI who obtains a license through their state regulatory department. There are certain steps taken when someone applies for a private investigator license that is in effect for the client's benefit more than the applicant's. Each state is different, however most states run a background check on the applicant through their state bureau, some also take it a step further and run an FBI background check on the applicant.
When applying for a private investigator license, most states administer a test to gauge knowledge of local and state stalking laws, and other laws pertaining to the work a private investigator will do. It is always best to use a licensed professional that will be mindful of laws relating to their field, you don't want to have an investigator commit a crime and say they did it for you, the client.
Applicants also are usually required to purchase liability insurance, which protects both the applicant and the client should damages or incidents resulting in a loss for the client should occur. All in all it is more cost effective and could potentially save you time, money, and possibly from going to court, if you hire a professional with a license.