If you or someone you know is being investigated by police for an alleged crime, it is important to understand how the investigation process works. In order to arrest someone, the police must be able to establish probable cause that they committed a crime, which means they must conduct a pre-arrest criminal investigation before they can take action. This article explains how the police and prosecution do this.
When a crime occurs, police officers and detectives will usually begin an investigation on the scene. They may stop the crime in progress, apprehend offenders or suspects, and collect physical evidence from the scene such as blood stains, weapon marks, clothing and other items. Crime scene investigators, often known as CSIs, are specially trained to note and document all details at the crime scene. Other evidence can be gathered from witnesses who are interviewed by police or detectives. Interrogation is a part of the investigative process that is highly regulated because it is a tool for gathering information that can be used to gain a confession from the suspect, who is usually unaware they are being interrogated.
Surveillance, including wiretapping and electronic monitoring of a suspect are also common investigative tools in modern law enforcement, though they are generally subject to strict courtroom limitations. Medical examinations of suspects are sometimes employed as a way to find out what injuries they suffered during the crime. Other forms of evidence are collected in a crime laboratory, including fingerprinting, voiceprinting and DNA analysis. When the investigation is complete, the police or the Crown Prosecution Service will decide whether to prosecute a suspect. Victims who are unhappy with the decision can request a review through the victim’s rights scheme.
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