Check their year in business as an actual private investigator, not the combined time of the investigators in their office. Many investigators will try to mislead their clients in their advertising by combining all total years of investigators in the office. So if they add up the years of experience from 8 investigators in their office they will say “40 years of experience!” But that is incredibly misleading.
How can you tell how many years they have been licensed? Look at their private investigator state license number; the lower the number, the longer the time they’ve been in business for themselves. Never hire an investigations company that is not owned by a licensed investigator. Many online investigative services are merely brokers, subcontracting cases to actual PI’s with less experience. This is dangerous to the confidentiality of your case; another thing about it is that you are likely not getting the most qualified investigator and your money is not being well-spent.