Private detectives and investigators (PI) may provide assistance in civil liability and personal injury cases, insurance claims and fraud, child custody and protection cases, martial infidelity cases and premarital screening. They also offer pre-employment verification and executive, corporate, and celebrity protection. Detectives may make phone calls or visit a subject's workplace to verify facts. In missing persons and background check cases, investigators (PI) often interview people to gather as much information as possible about an individual.