A police investigation is an officer’s process of gathering evidence to determine if there was a crime committed and who the suspect(s) might be.
Officers investigate a range of incidents including criminal offences, anti-social behaviour, missing persons and road traffic collisions. Some investigations are complex or serious and are assigned to specialised investigators (detectives). All officers are trained to investigate offences, but they also receive specialist training for investigating more specialised types of crimes like homicide, cybercrime and narcotics.
The starting point of an investigation is a report from a victim or witness. The report will be recorded and then an investigator will decide whether or not to investigate the incident. This decision will be made by either the duty inspector or an investigating officer. The investigating officer will then be authorised to start the investigation and follow specific procedures set out by their force.
Investigations will usually involve interviewing victims, witnesses and suspects. This may include face-to-face interviews and written statements. Officers will also collect physical items from the crime scene. These will be carefully handled to avoid contamination and preserved for forensic examination. Officers will document each item of evidence and establish an unbroken chain of custody from the moment it is collected to when it is presented at court.
Investigators will use other methods to gather evidence such as surveillance and analysing public records and databases. They will also consider how the investigation is affected by specific groups of people such as children, vulnerable adults or those with protected characteristics.
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