A detective is an officer of the police that performs criminal or administrative investigations, or a private person licensed to investigate information not readily available in public records (also called private eye). It can be also used for any unlicensed person who solve crime, including historical crimes (as in fiction for example) or looks into records.

Table of contents
1 Detectives and their work
2 Organization of detectives
3 Techniques of detectives
4 Famous detectives

Detectives and their work

Becoming a detective

In most American police departments, a candidate for detective must have served as a uniformed officer for a period of one to five years before becoming qualified for the position.

Detectives obtain their position by competitive examination, covering such subjects as:

  • Principles, practices, and procedures of investigations
  • Principles, practices, and procedures of interviewing and interrogation
  • Local criminal law and procedures
  • Applicable law governing arrests, search and seizures, warrants, and evidence
  • Police department records and reports
  • Principles, practices and objectives of courtroom testimony
  • Police department methods and procedures

Private detectives are licensed by the state in which they live after passing a competitive examination and a criminal background check. Some states, such as Maryland, require a period of classroom training as well.

Organization of detectives

The detective bureau in most police departments is organized into several squads, each of which specializes in a type of investigation such as:

Techniques of detectives

Street work

Detectives have a wide variety of techniques available in conducting investigations. However, the majority of cases are solved by interrogation of suspects and witnesses, which takes time. In a policeman?s career as a uniformed officer and as a detective, a detective develops an intuitive sense of the plausibility of suspect and witness accounts. This intuition may fail at times, but usually is reliable.

Besides interrogations, detectives may rely on a network of informants he or she has cultivated over the years. Informants often have connections with persons a detective would not be able to approach formally.

In criminal investigations, once a detective has a suspect or suspects in mind, the next step is to produce evidence that will stand up in a court of law. The best way is to obtain a confession from the suspect, usually in exchange for a plea bargain for a lesser sentence. A detective may lie or otherwise mislead and may psychologically pressure a suspect into confessing, though in the United States a suspect may invoke his or her Miranda rights.

Forensic evidence

Physical forensic evidence in an investigation may provide leads to closing a case.

Examples of physical evidence can be, but are not limited to:

  • Fingerprinting of objects persons have touched
  • DNA analysis
  • Luminol to detect blood stains that have been washed
  • Footprints or tire tracks
  • Chemical testing for the presence of narcotics or expended gun propellant
  • The exact position of objects at the scene of an investigation

Many major police departments in a city, county, or state, and the Federal Bureau of Investigation, maintain their own forensic laboratories.

Records investigation

Detectives may use public and private records to provide background information on a subject. These include:

  • Fingerprint records. In the United States, the FBI maintains records of people who have committed felonies and some misdemeanors, all persons who have applied for a Federal security clearance, and all persons who have served in the U.S. armed forces
  • Records of criminal arrests and convictions
  • Photographs or mug shots, of persons arrested
  • Motor vehicle records
  • Credit card records and bank statements
  • Hotel registration cards
  • Credit reports

Court testimony

Unless a plea bargain forestalls the need for a trial, a detective must testify in court about his investigation. He or she must seem reliable and credible to a jury, and must not give the impression of personal vindictiveness or cruelty. A detective's background often comes into question in courtroom testimony. A famous example came in the murder trial of O. J. Simpson, when Detective Mark Fuhrman of the Los Angeles Police Department testified for the prosecution. Attorney F. Lee Bailey first asked Furhman if he had ever used the "n-word" (see Nigger). Furhman denied this. In court, Bailey produced taped interviews with Furhman using this offensive word.

Famous detectives

Fictional detectives

The detective story has been a popular genre in books, radio, television, and movies since the early 19th century.

Famous fictional detectives include:

Unlicensed detectives include: Hercules Poirot and Miss Jane Marple, both created by Agatha Christie.

See Detective fiction and Crime fiction for more details.

See also: