The detective branch in most larger police agencies is organized into several squads or departments, each of which specializes in investigation into a particular type of crime or a particular type of undercover operation, which may include: homicide; robbery; burglary; auto theft; organized crimes; missing persons; fraud; narcotics; vice; criminal intelligence; aggravated assault/battery; sexual assault; computer crime; domestic violence; surveillance; and arson, among others.
Techniques
Street work
Detectives have a wide variety of techniques available in conducting investigations. However, the majority of cases are solved by the interrogation of suspects and the interviewing of witnesses, which takes time. Besides interrogations, detectives may rely on a network of informants they have cultivated over the years. Informants often have connections with persons a detective would not be able to approach formally. Evidence collection and preservation can also help in identifying a potential suspect(s).
Criminal investigation : the investigation of criminal activity is conducted by the police. Criminal activity can relate to road use such as speeding, drunk driving, or to matters such as theft, assault, fraud , etc. When the Police have concluded their investigation a decision on whether to charge somebody with a criminal offense will often be made by the Director of Public Prosecutions (DPP) having considered the evidence produced by the Police.
In criminal investigations, once a detective has 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, this is done by developing rapport and at times by seeking information in exchange for potential perks available through the District Attorney's Office, such as entering plea bargain for a lesser sentence in exchange for usable information. Detectives may lie, mislead and psychologically pressure a suspect into an admission or confession as long as they do this within procedural boundaries and without the threat of violence or promises outside their control. In the United States suspects may invoke their Fifth Amendment rights and refuse to answer any investigative questions until they consult with an attorney.
Forensic evidence
Physical forensic evidence in an investigation may provide leads to closing a case. Forensic science (often shortened to forensics) is the application of a broad spectrum of sciences to answer questions of interest to the legal system. This may be in relation to a crime or to a civil action.
The use of the term "forensics" in place of "forensic science" is (in a literal sense) incorrect; the term "forensic" is effectively a synonym for "legal" or "related to courts" (from Latin, it means "before the forum") and applies equally well to studies such as "forensics clubs" that practice formal debate. However, the single word is now so closely associated with the scientific field that many dictionaries include the meaning given here. 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. Police detectives can search through files of 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. As well, detectives may search through records of criminal arrests and convictions, photographs or mug shots, of persons arrested, and motor vehicle records.
With a warrant, police detectives can also search through Credit card records and bank statements, hotel registration information, credit reports, Answer machine messages, and phone conversations. Search warrants are not needed if the detective can obtain a National Security Letter (NSL) from the FBI or other federal agency. These are generally issued without significant oversight or probable cause.
All text of this article available under the terms of the GNU Free Documentation License (see Copyrights for details).