Criminal law and procedure relevant to investigative work
Criminal law for investigators
Know the offenses you may encounter: trespass, burglary, stalking, harassment, threats, assault, theft, fraud, identity theft, impersonation, obstruction, and Oklahoma communications or wiretap violations. Private investigators are not police officers. They generally have no greater arrest or search authority than a private citizen. Citizen's arrest authority is narrow and risky, and force may be used only within lawful self-defense or defense-of-others limits.
Procedure and evidence
Fourth Amendment search-and-seizure rules and Miranda warnings generally bind government actors. A private investigator may become a state agent if police direct or control the investigator's actions, which can trigger constitutional limits. Private searches can still be tortious or criminal. Preserve evidence, document chain of custody, avoid contaminating witnesses, and separate observed facts from opinions in reports.
Worked example
An investigator interviews a suspect for a private employer. No Miranda warning is required because the investigator is not police and there is no state action. But if police direct the investigator to conduct the interview to avoid Miranda, the investigator may be treated as a police agent, and the statements could be suppressed. If the investigator blocks the exit or threatens the suspect, false imprisonment or other liability may arise.
Traps
Do not Mirandize unnecessarily or assume private status excuses trespass. Do not conduct searches without consent or lawful authority. Threats, deception about legal authority, and mishandling digital evidence can create criminal and civil exposure.