A private investigator or private detective is a person who secretly follows and observes persons in public places for the purpose of witnessing behavior and collecting evidence of any illegal or improper activities (photos, videos, etc.). During the divorce process a spouse who suspects their spouse of cheating (adultery) or other improper or illegal behavior may hire a private investigator to follow or “tail” the other spouse.

In New Hampshire, private investigators are regulated under state law and must be licensed to legally conduct surveillance and investigative work. The New Hampshire Department of Safety, Division of State Police is responsible for the licensing and oversight of private investigators. According to NH Rev Stat § 106-f:4, individuals must meet certain requirements, including passing a background check and having professional liability insurance, to obtain a license. When hired during a divorce process to investigate suspicions of adultery or other improper behavior, private investigators must operate within the bounds of the law. This means they are permitted to observe and collect evidence in public places, but they must not engage in illegal activities such as trespassing, invasion of privacy, or harassment. Evidence gathered by a licensed private investigator can be used in court proceedings, including divorce cases, provided it was obtained legally. It's important for anyone considering hiring a private investigator to consult with an attorney to ensure that the investigation is conducted lawfully and the evidence is admissible in court.