When a private investigator is not part of any agency, then he or she can be termed as an independent investigator. This person does not become part of any kind of detective or investigative agency, as he prefers to work on his own. He is completely responsible for all his actions and inactions as a  private investigator . Once you have hired him, it is his duty to complete the job and report to the client within the specified time. The amount of money that he charges will be a lot more than what the others charge.