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Authorised Professional Practice

This page is from APP, the official source of professional practice for policing.


The Code of Practice to the Criminal Procedure and Investigations Act 1996 (CPIA) defines a criminal investigation as:

An investigation conducted by police officers with a view to it being ascertained whether a person should be charged with an offence, or whether a person charged with an offence is guilty of it.

Investigators conducting an investigation should impartially follow all reasonable lines of enquiry to gather material which points both towards and away from a suspect. This process may result in the suspect being prosecuted in the courts, an out-of-court disposal or community resolution.

The Home Office (2020) Counting rules for recorded crime states that, when making a complaint, victims should be believed for the purposes of recording a crime, unless it is clear at that point that the incident did not happen.

Investigators should proportionately test material gathered through enquiries, including victim and witness accounts, and use technical and scientific expertise to maximise evidential opportunities. Effective case management and disclosure will support prosecutors and the criminal justice process to achieve successful outcomes.

In many cases an investigation will not find enough material to make a charging decision. This may be because the offender has left very little evidence or there are no viable lines of enquiry to pursue. In these cases it is still important to accurately record the outcome of the investigation for intelligence purposes. This will help the police service to identify crime hot spots and take proactive action to reduce risk and prevent further crimes. In some cases the process of an investigation will also help victims to recover from the impact of crime and access appropriate support services.

Throughout the investigation and criminal justice process, victims should be supported according to their diverse needs, allowing them to give their best evidence. Any risks should be effectively managed and they should be directed to appropriate support services.

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