A private investigator or private detective (often shortened to PI or private eye) is a person who can be hired by individuals or groups to undertake investigations. Private investigators often work for attorneys in civil cases. Many work for insurance companies to investigate suspicious claims. Before the advent of no-fault divorce, many private investigators were hired to search out evidence of adultery or other illegal conduct within marriage to establish grounds for a divorce. Despite the lack of legal necessity for such evidence in many jurisdictions, according to press reports collecting evidence of adultery or other "bad behaviour" by spouses and partners is still one of the most profitable activities investigators undertake, as the stakes being fought over now are child custody, alimony, or marital property disputes.
Many jurisdictions require PIs to be licensed, and they may or may not carry firearms depending on local laws. Some are ex-police officers, some are former federal agents, some are ex-spies and some are ex-military, some used to work in a Private military company, some are former bodyguards and Security guards, although many are not. Most of them do not arrest criminals or put them in custody. They are expected to keep detailed notes and to be prepared to testify in court regarding any of their observations on behalf of their clients. Great care is required to remain within the scope of the law, otherwise the investigator may face criminal charges. Irregular hours may also be required when performing surveillance work.
PIs also engage in a large variety of work that is not usually associated with the industry in the mind of the public. For example, many PIs are involved in process serving, the personal delivery of summons, subpoenas and other legal documents to parties in a legal case. The tracing of absconding debtors can also form a large part of a PI's work load. Many agencies specialize in a particular field of expertise. For example, some PI agencies deal only in tracing. Others may specialize in technical surveillance countermeasures (TSCM), or Electronic Counter Measures (ECM), which is the locating and dealing with unwanted forms of electronic surveillance (for example, a bugged boardroom for industrial espionage purposes). Other PIs, also known as Corporate Investigators, specialise in corporate matters, including anti-fraud work, the protection of intellectual property and trade secrets, anti-piracy, copyright infringement investigations, due diligence investigations and computer forensics work.
Increasingly, modern PIs prefer to be known as "professional investigators" or Licensed Private Investigators (LPI's) rather than "private investigators" or "private detectives". This is a response to the image that is sometimes attributed to the profession and an effort to establish and demonstrate the industry to be a proper and respectable profession.

History of the private investigator

In 1833 Eugène François Vidocq, a French soldier, criminal and privateer, founded the first known private detective agency, "Le Bureau des Renseignements Universels pour le commerce et l'Industrie" ("The Office of Universal Information For Commerce and Industry") and hired ex-convicts. Official law enforcement tried many times to shut it down. In 1842 police arrested him in suspicion of unlawful imprisonment and taking money on false pretences after he had solved an embezzlement case. Vidocq later suspected that it had been a set-up. He was sentenced for five years with a 3,000-franc fine but the Court of Appeals released him. Vidocq is credited with having introduced record-keeping, criminology and ballistics to criminal investigation. He made the first plaster casts of shoe impressions. He created indelible ink and unalterable bond paper with his printing company. His form of anthropometrics is still partially used by French police. He is also credited for philanthropic pursuits – he claimed he never informed on anyone who had stolen for real need.
After Vidocq, the industry was born. Much of what private investigators did in the early days was to act as the police in matters that their clients felt the police were not equipped for or willing to do. A larger role for this new private investigative industry to was to assist companies in labor disputes. Some early private investigators provided armed guards to act as a private militia.
In the United Kingdom, the Hungarian, Ignatius Paul Pollaky, set up an agency in 1862. Although little remembered today, his fame at the time was such that he was mentioned in various books of the 1870s and immortalized as "Paddington" Pollaky for his "keen penetration" in the comic opera, Patience.

In the U.S., the Pinkerton National Detective Agency was a private detective agency established in 1850 by Allan Pinkerton. Pinkerton had become famous when he foiled a plot to assassinate then President-Elect Abraham Lincoln. Pinkerton's agents performed services which ranged from undercover investigations and detection of crimes to plant protection and armed security. It is sometimes claimed, probably with exaggeration, that at the height of its existence the Pinkerton National Detective Agency employed more agents than the United States Army.
During the labor unrest of the late 19th century, companies sometimes hired operatives and armed guards from the Pinkertons and similar agencies to keep strikers and suspected unionists out of their factories. The most famous example of this was the Homestead Strike of 1892, when industrialist Henry Clay Frick hired a large contingent of Pinkerton men to regain possession of Andrew Carnegie's steel mill during a lock-out at Homestead, Pennsylvania. Gunfire erupted between the strikers and the Pinkertons, resulting in multiple casualties and deaths on both sides. Several days later a radical anarchist, Alexander Berkman, attempted to assassinate Frick. In the aftermath of the Homestead Riot, several states passed so-called "anti-Pinkerton" laws restricting the importation of private security guards during labor strikes. The federal Anti-Pinkerton Act of 1893 continues to prohibit an "individual employed by the Pinkerton Detective Agency, or similar organization" from being employed by "the Government of the United States or the government of the District of Columbia."
Pinkerton agents were also hired to track western outlaws Jesse James, the Reno brothers, and the Wild Bunch, including Butch Cassidy and the Sundance Kid. The Pinkerton agency's logo, an eye embellished with the words "We Never Sleep," inspired the term "private eye."

It was not until the prosperity of the 1920s that the private investigator became a person accessible to the average American. With the wealth of the 1920s and the expanding of the middle class came the need of middle America for private investigators.
Since then the private detective industry has grown with the changing needs of the public. Social issues like infidelity and unionization have impacted the industry and created new types of work, as has the need for insurance and, with it, insurance fraud, criminal defense investigations and the invention of low-cost listening devices. In a number of countries, a licensing process has been introduced that has put criteria in place that investigators have to meet: in most cases, a clean criminal record. This has combined with modern business practices that have ensured that most investigators are now professional in outlook, rather than seeing the PI world as a second career opportunity for retired policemen.

Private investigators in fiction

The PI genre in fiction dates back to Edgar Allan Poe who created the character C. Auguste Dupin, who lived in Paris. The genre spread to films, radio and television, including USA Network's Psych, and remains popular to this day in many forms of media. (See Mystery film for details on the history of movies featuring private detectives.)

See also

• Anthony Pellicano (born March 22, 1944, in Chicago, Illinois) is a former high-profile Los Angeles private investigator who recently served a sentence of three and a half years in federal prison for illegal possession of explosives, firearms and homemade grenades, and who was arrested on February 4, 2006, on unlawful wiretapping and racketeering charges.