Private investigators first known agency, Le Bureau de Renseignements Universels pour le commerce et l’Industrie, was founded in 1833 by French soldiers Eugene Francois Vidocq Who was also a criminal and privateer. This private investigator agency hired ex-convicts who carried out investigations and other private detective duties but were frowned upon by the official law enforcement who tried to shut down the operation on many occasions. On one occasion in 1842, after solving a case of embezzlement, Vidocq was arrested by police for suspicion of unlawful imprisonment and taking money on false pretences.

He was sentenced to five years imprisonment and fined 3,000 francs; he was later released by the Court Of Appeals. At the time Vidocq was doubtful of the conviction and felt that he had been set up. Despite his negative past his attributes include introducing record keeping, criminology and ballistics into criminal investigations.
Along with making the first plaster cast of a shoe and he created a form of anthropometry that is still used by the French police force today and through his own printing company, he invented indelible ink and unchangeable bond paper. Through the private detective company that Vidocq set up in France the private investigator industry was born.

Most of the early private investigators acted as police in cases where the client thought that police officers were not interested or prepared to do.
Many of the roles undertaken by these modern private detectives included helping businesses with labour disputes and in many cases they were employed as armed security guards.

Later in 1852,Charles Frederick Field, a private investigator in London, started an enquiry office when he retired from the Metropolitan Police.
Field was a friend of the writer Charles Dickens who would often accompany police officers on their nightly rounds and in 1851 Dickens wrote a short essay “On Duty with Inspector Field” and it is suggested that he based his “Bleak House” character Inspector Bucket on Field.

Over the pond in the United States, Allan Pinkerton set up the Pinkerton National Detective Agency in 1850 and became famous when he uncovered and hindered an assassination attempt on the then President-elect Abraham Lincoln in 1861. Services provided by Pinkerton National Detective Agency included undercover investigations, crime detection and supplying security guards who were often armed. Among the many private investigators that formed the workforce of Pinkerton National Detective Agency in 1856 Pinkerton hired the first female private detective in America, Kate Warne.

It is understood that in the United States in the late 19th century during the union unrest Pinkerton private detectives were made available for hire as armed security guards for companies to protect them. After the Homestead Riots of 1892 several states brought in “Anti Pinkerton” laws restricting the use of imported security guards during union strikes. The federal Anti Pinkerton Act of 1893 prohibits an “individual employed by the Pinkerton Detective Agency or similar organisation” from being employed. Pinkerton agents were hired to track down outlaws like Jesse James, the Reno brothers, Butch Cassidy and the Sundance Kid.

The term “Private Eye” comes from the Pinkerton logo of an eye adorned with the words “We Never Sleep”.