There are numerous opportunities to become a successful private investigator. First of all, many individuals hire private investigators to investigate things like divorce cases, most commonly to investigate suspicions of adultery or bad conduct within a family. A jilted spouse will often contact a private investigator to conduct surveillance on the wayward spouse. Other private individuals may hire PIs to locate missing family members, or to identify assets that someone (a spouse?) is believed to be hiding.

Businesses may hire PIs to do pre-employment or background checks, or undercover work as an "employee". Insurance companies hire private investigators to investigate suspicious claims. Apartment complexes may hire PIs to do background checks on prospective tenants.

Perhaps the most important clients are attorneys and law firms that hire private investigators to collect evidence for civil cases going to trial, or to assist in the defense of a person accused of a crime.