A candidate must not be afraid of being confrontational, should communicate well, and should be able to think on his or her feet. Good interviewing and interrogation skills are important and are usually acquired in earlier careers in law enforcement or other fields. The courts are often the ultimate judge of a properly conducted investigation, so the investigator must be able to present the facts in a manner a jury will believe. Almost all private detectives and investigators have previous experience in other occupations. Some work initially for insurance or collections companies or in the security industry.
Many investigators enter the field after serving in military or law enforcement jobs.
Retired law enforcement officers, military investigators, and government agents frequently become private detectives and investigators as a second career. Others enter from such diverse fields as finance, accounting, investigative reporting, insurance, and law. These individuals often can apply their prior work experience in a related investigation specialty. A few enter the occupation directly after graduation from college, generally with majors in such fields as criminal justice or police science. In most investigations firms, the screening process for potential employees includes a background check, to confirm education and work experience, to inquire about criminal history, and to interview references and others who know the applicant.