A private investigator (often abbreviated to PI and informally called a private eye), a private detective, or inquiry agent, is a person who can be hired by individuals, groups or
NGO A non-governmental organization, or simply an NGO, is an organization An organization, or organisation (Commonwealth English The use of the English language English is a West Germanic languages, West Germanic language first ...

s to undertake investigatory law services. Private investigators often work for
attorney Attorney may refer to: Roles * Attorney at law, an official title of lawyers in some jurisdictions * Attorney general, the principal legal officer of (or advisor to) a government * Attorney-in-fact, a holder of a power of attorney who is (though not ...

s in civil and criminal cases.


In 1833,
Eugène François Vidocq Eugène-François Vidocq (; 24 July 1775 – 11 May 1857) was a French Crime, criminal turned Forensic science, criminalist, whose life story inspired several writers, including Victor Hugo, Edgar Allan Poe and Honoré de Balzac. The former crimi ...
, a French
soldier A soldier is a person who is a member of a professional army An army (from Latin ''arma'' "arms, weapons" via Old French ''armée'', "armed" eminine, ground force or land force is a fighting force that fights primarily on land. In the ...

, criminal, and
privateer A privateer is a private person or ship that engages in maritime warfare under a commission of war. Since robbery under arms was a common aspect of seaborne trade, until the early 19th century all merchant ships carried arms. A sovereign or deleg ...
, 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 False imprisonment or unlawful imprisonment occurs when a person intentionally restricts another person’s movement within any area without legal authority Rational-legal authority (also known as rational authority, legal authority, rational ...
and taking money on false pretences after he had solved an
embezzlement Embezzlement is the act of withholding asset In financial accounting Financial accounting is the field of accounting Accounting or Accountancy is the measurement, processing, and communication of financial and non financial informa ...
case. Vidocq later suspected that it had been a set-up. He was sentenced to five years and fined 3,000
franc The franc is any of various units of currency. One franc is typically divided into 100 centimes. The name is said to derive from the Latin inscription ''francorum rex'' (Style of the French sovereign, King of the Franks) used on early France, F ...

s, but the Court of Appeals released him. Vidocq is credited with having introduced record-keeping,
criminology Criminology (from Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to b ...
, 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 Anthropometry, 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 for which their clients felt the police were not equipped or willing to do. A larger role for this new private investigative industry was to assist companies in labor disputes. Some early private investigators provided armed guards to act as a private militia. In the United Kingdom, Charles Frederick Field set up an enquiry office upon his retirement from the Metropolitan Police in 1852. Field became a friend of Charles Dickens, and the latter wrote articles about him. In 1862, one of his employees, the Hungarian Ignatius Paul Pollaky, left him and set up a rival agency. Although little-remembered today, Pollaky's 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 1881 comic opera, Patience (opera), ''Patience''. In the United States, Allan Pinkerton established the Pinkerton National Detective Agency – a private detective agency – in 1850. Pinkerton became famous when he foiled Baltimore Plot, a plot to assassinate then President-elect Abraham Lincoln in 1861. Pinkerton's agents performed services which ranged from undercover investigations and detection of crimes, to plant protection and armed security. At the height of its existence, the number of Pinkerton National Detective Agency active agents and reserves rivaled the number of active soldiers and reserves in the United States Army. Allan Pinkerton hired Kate Warne in 1856 as a private detective, making her the first female private detective in America. During the union unrest in the US in the late 19th century, companies sometimes hired operatives and armed guards from the Pinkertons. In the aftermath of the Homestead Strike, Homestead Riot of 1892, several states passed so-called "anti-Pinkerton" laws restricting the importation of private security guards during union 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 Gang, Reno brothers, and the Butch Cassidy's Wild Bunch, Wild Bunch, including Butch Cassidy and the Sundance Kid.


Many private detectives/investigators with special academic and practical experience often work with defense
attorney Attorney may refer to: Roles * Attorney at law, an official title of lawyers in some jurisdictions * Attorney general, the principal legal officer of (or advisor to) a government * Attorney-in-fact, a holder of a power of attorney who is (though not ...

s on capital punishment and other criminal defense cases. Others are insurance investigators who investigate suspicious claims. Before the advent of no-fault divorce, many private investigators sought evidence of adultery or other 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 spouses' and partners' adultery or other "bad behaviour" is not still one of their most profitable undertakings, as the stakes being fought over now are child custody, alimony, or marital property disputes. Private investigators can also perform due diligence for an investor considering investing with an investment group, fund manager, or other high-risk business or investment venture. This could help the prospective investor avoid being the victim of a fraud or Ponzi scheme. A licensed and experienced investigator could reveal the investment is risky and/or the investor has a suspicious background. This is called investigative due diligence, and is becoming more prevalent in the 21st century with the public reports of large-scale Ponzi schemes and fraudulent investment vehicles such as Madoff, Stanford, Petters, Rothstein, and the hundreds of others reported by the U.S. Securities and Exchange Commission, Securities and Exchange Commission along with other law enforcement agencies. In some cases, PIs are hired by NGOs, e.g. to rescue girls from sex traffickers. However, there are also cases of Corruption, corrupt private detectives who, at times, have been known to work for criminals such as Stalking, stalkers and crime lords/drug lords to track down escaped victims, rival criminals and/or witnesses that have gone into hiding or to gather compromising evidence against witnesses, informants, prosecutors and/or police investigators, that could be used in upcoming trials.


Private investigators also engage in a variety of work not often associated with the industry in the mind of the public. For example, many are involved in service of process, 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. A handful of firms specialize in technical surveillance counter-measures, sometimes called electronic counter measures, which is the locating and dealing with unwanted forms of electronic surveillance (for example, a bugged boardroom for industrial espionage purposes). This niche service is typically conducted by those with backgrounds in intelligence/counterintelligence, executive protection, and a small number from law enforcement entities whose duties included the covert installation of eavesdropping devices as a tool in organized crime, terrorism and narco-trafficking investigations. Other PIs, also known as corporate investigators, specialize in corporate matters, including antifraud work, loss prevention, internal investigations of employee misconduct (such as Equal Employment Opportunity Commission, Equal Employment Opportunities violations and sexual harassment), the protection of intellectual property and trade secrets, antipiracy, copyright infringement investigations, due diligence investigations, malware and cyber criminal activity, and computer forensics work. Some PIs act as professional witnesses where they observe situations with a view to reporting the actions or lack of them to a court or to gather evidence in antisocial behavior.

Undercover investigator

An undercover investigator, undercover detective, or undercover agent is a person who conducts investigations of suspected or confirmed criminal activity while impersonating a disinterested third party. Undercover investigators often infiltrate a suspected insurgent group, posing as a person interested in purchasing illegal goods or services with the ultimate aim of obtaining information about their assigned target. Many undercover investigators carry hidden cameras and recorders strapped to their bodies to help them document their investigations. The period of the investigation could last for several months, or in some extreme cases, years. Due to the dangerous nature of the job, their real identities are kept secret throughout their active careers. Economic investigations, business intelligence and information on competitors, security advice, special security services information, criminal investigation, investigations background, and profile polygraph tests are all typical examples of such a role. Certain types of undercover investigators, depending on their employer, will investigate allegations of abuse of workman's compensation. Those claiming to be injured are often investigated and recorded with a hidden camera/recorder. This is then presented in court or to the client who paid for the investigation.

Across the world

Many jurisdictions require PIs to be licensed. Depending on local laws, they may or may not carry a firearm. Equipment can vary greatly, but generally involves a wide variety of Surveillance#methods, surveillance equipment and recording devices. While PIs may investigate criminal matters, they typically do not hold any law enforcement agency powers, law enforcement authority by virtue of the position, regardless of licensure. Private investigators’ authority is usually identical to other citizens’ (off-duty or retired law enforcement officers serving as a PI may retain their police powers at all times, depending on the jurisdiction). 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.


Private investigators in Australia must be licensed by the licensing authority relevant to the state where they are located. This applies to all states except the Australian Capital Territory. Companies offering investigation services must also hold a business licence and all their operatives must hold individual licences. Generally, the licences are administered and regulated by the state police; however, in some states, this can also be managed by other government agencies. To become registered in New South Wales requires a CAPI licence, which can be applied for through the NSW Police Force website. The Australian Capital Territory does not require PIs to be licensed, although they are still bound by legislation. PIs working in the ACT cannot enter the NSW area without a CAPI license, else they will be in breach of the law. In Queensland, a private investigator need to be licensed under the Queensland Government and apply for a private investigator licence by completing an application for a security provider licence. Applicant will need to have a criminal history check and submit fingerprint.


In 2001, the government passed the licensing of private investigators and private investigation firms in the UK over to the Security Industry Authority (SIA), which acted as the regulatory body from then on. However, due to the cutbacks of this agency, licensing of private investigators in the UK was halted indefinitely. At present, no government-backed authorities in the UK license private investigators. The SIA have announced that PIs in the UK were to become licensed for the first time from May 2015, but this is only the scheduled date for the issue to be discussed in parliament. In December 2014, Corporate Livewire produced an article written by a UK private investigator at BAR Investigations, addressing the issues surrounding private investigation in the UK.

United States

Private investigators in the United States may or may not be licensed or registered by a government licensing authority or state police of the state where they are located. Licensing varies from state to state and can range from: a) no state license required; b) city or state business license required (such as in five states (Idaho, Alaska, Mississippi, South Dakota, and Wyoming); c) to needing several years of experience and licensing-related training classes and testing (as is the case with Virginia, West Virginia, and California). In many states, companies offering investigation services must hold an agency license, and all of their investigators or detectives must hold individual licenses or registrations; furthermore, certain states such as Washington (state), Washington have separate classes of licensing for roles such as trainers of private investigators. A few reciprocity agreements allow a detective working in one state to continue work in another for a limited time without getting a separate license, but not all states participate in these agreements. In 1877, Colorado became the first state in the union to institute licensing requirements for private investigators, as stated in the 1877 Legislative Manual. In 1977, when El Paso County, Colorado, El Paso County challenged a local security company's right to conduct investigations without a license, Colorado Supreme Court declared the licensing law too vague because it didn't adequately define a "detective business" and struck it down. Following this, several private investigators formed Professional Private Investigators Association of Colorado (PPIAC) in order to try to get the licensing laws reinstated, but the bills died in the General Assembly. On June 10, 2011, Governor of Colorado, Governor John Hickenlooper signed into law Colorado House Bill 1195, which reinstated licenses for private investigators on voluntary basis effective July 1, 2012. An license applicant would have to be of 21 years of age or older, hold United States citizenship and have at least 4,000 hours of work experience as an investigator or part of a local, state or federal law enforcement agency; or 2,000 hours with post-secondary education. On June 6, 2014, Hickenlooper signed into law Senate Bill 133, which effective June 1, 2015, made licensure mandatory. This split the licenses into two categories: Class I, requiring the applicant to be 21 years of age or older, hold United States citizenship and pass the Colorado Jurisprudence Exam. Class II requires in addition to Class I requirements a minimum of 4,000 hours of work experience as an investigator or part of a local, state or federal law enforcement agency. In 2019, following a review, the Colorado Department of Regulatory Agencies' Office of Policy, Research and Regulatory Reform suggested licensure requirement elimination, predicting "little to no consumer harm". In June 2020, Governor Jared Polis vetoed House Bill 1207 to keep licensure requirements, causing the licensure requirements to expire on August 31, 2021. Florida has 3 types of licenses - Class CC for private investigator intern, C for private investigator, and MA for manager of a private investigative agency. As Class C license requires at least 2 years of experience, most applicants start with Class CC, which allows them to work under a sponsorship of a licensed Class C investigator. For a Private Investigator License in New York, an investigator needs 3 years of verifiable experience, and to pass a NY State Department of State Division of licensing Services exam. In 1893 Anti-Pinkerton Act, a federal law was passed explicitly barring the government from employing the Pinkerton Detective Agency or a similar agency.


Private investigators in Canada are licensed at the provincial level by the appropriate body. For instance, in the province of Ontario, private investigators are licensed and regulated by the Ministry of Community Safety & Correctional Services (MCSCS). In the province of Alberta, private investigators are licensed and regulated by the Alberta Justice and Solicitor General. Similar licensing requirements apply in other provinces and territories of Canada. As per the Ontario text of th
Private Security and Investigative Services Act of 2005
private investigators are forbidden from referring to themselves as detective or private detective. In order to become a licensed private investigator, you must be 18 years of age or older in Ontario (in other Provinces and territories of Canada the eligible age to work may be higher); have a clean criminal record or obtain a waiver; and submit a correctly completed application for a license. You are required to complete 50-hours of basic training with an accredited source such as a university, college, or through private agencies licensed to administer the course. Upon completion of basic training, individuals are required to write and pass the basic test to obtain a private investigator's license.


The PI genre in fiction dates to Edgar Allan Poe, who created the character C. Auguste Dupin in the 1840s. Dupin, an amateur crime-solver residing in Paris, appeared in three Poe stories.

Notable private investigators

In reality

* P. Balasubramaniam * Rick Crouch * David Fechheimer * Charles Frederick Field * Dashiell Hammett (also a notable author of detective fiction) * Justin Hopson * Anthony Pellicano * Allan Pinkerton * Josiah Thompson, Josiah "Tink" Thompson * Kate Warne * David P. Weber

In fiction

Where the characters below do not meet the strict criteria of a private investigator (i.e. available for hire) it is noted in brackets.


*Harry Dresden *Mike Hammer *Philip Marlowe *Kinsey Millhone *Ezekiel "Easy" Rawlins *John Shaft *Sam Spade *Spenser (character), Spenser *V. I. Warshawski *Nero Wolfe *Jack Reacher *Jim Rockford (television character), Jim Rockford *Sunny Randall


*Arjun (character), Arjun *Byomkesh Bakshi *Parashor Barma *Feluda *Jayanta-Manik *Mitin Masi *Bhaduri Moshai *Kiriti Roy *Colonel Niladri Sarkar *Goenda Baradacharan


*Auguste Dupin *Marcus Didius Falco *Erast Fandorin *Sherlock Holmes *Tintin (character), Tintin *Miss Marple *Hercule Poirot *Mma Precious Ramotswe *Cormoran Strike *Varg Veum

=Comics, graphic novels, and manga

= *''The Adventures of Tintin, Tintin'' *''Case Closed, Detective Conan'' *''The Kindaichi Case Files'' *''Jessica Jones'' *''Rip Kirby'' *''L. Lawliet'' *''Sam & Max'' *''Dick Tracy'' *''Eddie Valiant'' *Calvin and Hobbes, Tracer Bullet

Film and television

*Paul Drake (character), Paul Drake (Perry Mason) *Angel (Buffy the Vampire Slayer) *Chip n' Dale from Chip 'n Dale: Rescue Rangers (TV series), Rescue Rangers iterations. *Phryne Fisher *Remington Steele, Laura Holt *Thomas Magnum *Richard Castle *Jessica Jones *Joe Mannix *Veronica Mars (character) , Veronica Mars *Michael Westen *Adrian Monk *Jim Rockford (television character), Jim Rockford *Simon & Simon *Shawn Spencer *Sherlock Hound *Hetty Wainthropp *Frank Marker *Frankie Drake Mysteries, Frankie Drake

Children's fiction

*Basil of Baker Street *The Bloodhound Gang (TV series), The Bloodhound Gang (Amateur juvenile detectives) *Nancy Drew (Amateur juvenile detective) *The Hardy Boys (Amateur juvenile detectives) *Three Investigators (Amateur juvenile detectives) *Encyclopedia Brown (Amateur juvenile detective)

In games

*Booker DeWitt (''BioShock: Infinite'') *Tex Murphy#The character, Tex Murphy (''Tex Murphy'') *Sam & Max#Overview, Sam & Max (''Sam & Max'') *Gabriel Knight#Characters, Gabriel Knight (''Gabriel Knight'') *Nick Valentine (''Fallout 4'') *Paul Prospero (''The Vanishing of Ethan Carter'') *Takayuki Yagami (''Judgment (video game), Judgment'')

See also

*Bounty hunter *Detective **Hotel detective **Store detective *Insurance investigator *Investigative journalism *Mercenary **Private Military Companies *Mystery film *Numerical analysis software : i.e. SAS (software), SAS, Palantir Technologies GothamVice Motherboard article on Palantir
/ref> *Private police **Company police *World Association of Detectives


External links

Bureau of Labor Statistics information
{{DEFAULTSORT:Private Investigator Private detectives and investigators, Criminal investigation Law enforcement occupations