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Understanding the process, your role and obligations

The role and obligations of the investigator.

First published
Conducting effective investigations

In carrying out an investigation, investigators must:

  • identify and follow all reasonable lines of enquiry to gather all reasonably available material and, where a suspect is identified, investigate towards and away from the suspect (Criminal Procedure and Investigations Act 1996, (CPIA))
  • treat victims with fairness and respect, and ensure that they are afforded their rights under the Victims’ Code

What is reasonable and proportionate in each case will depend on the particular circumstances and will depend on the stage of the investigation. There may also be local governance or policy regarding this. It is a matter for the investigator to decide what constitutes a reasonable line of enquiry in each case. Depending on the stage of the investigation, this can be done with the assistance of the prosecutor if required.

In addition, investigators should:

  • understand their contribution to, and role and obligations within, the criminal justice process
  • be professionally curious, ask searching questions and employ effective communication skills
  • assess the threat, risk and harms to victims, witnesses and suspects, as well as their needs, and take appropriate action
  • strive to achieve best outcomes for all

Evidence summary

Overall, there is moderate evidence supporting this guideline. The evidence review found good evidence that open-mindedness helps ensure that investigations are run effectively and helps to protect investigators from confirmation bias. Open-mindedness is a key part of professional curiosity, the importance of which is also supported by evidence from the vulnerability-related risk guidelines REA.

It is important that officers understand the impact that the initial response to a crime can have on an investigation. Some evidence from homicide investigations suggests that the speed and quality of the initial response to serious crimes is important, as certain forms of evidence are likely to be more difficult to retrieve later.

There was some evidence that understanding the court process supports effective investigations. However, research evidence on the importance of investigators understanding their contribution to – and their role and obligations within – the criminal justice process was limited. Practitioner evidence suggests that having an understanding of the court process, wider outcomes and the points to prove, as well as considering evidential issues and the bigger picture, is essential to an effective investigation.

There is good evidence on the importance of effective communication and the use of questions for an effective
investigation. This is summarised in vulnerability-related risk, obtaining initial accounts, conflict management and neighbourhood policing guidelines. Practice evidence also supported the importance of asking questions and employing effective communication for an effective investigation.

There is strong evidence that victim satisfaction is associated with how a victim is treated during the criminal justice process and not necessarily by the outcome alone. There is also strong evidence that alternative criminal justice outcomes to prosecution (for example, restorative justice) can be effective.

Empirical evidence
Practitioner evidence

Understanding the criminal justice process and your obligations

The main obligations for investigators are set out in the Criminal Procedure and Investigations Act 1996 (CPIA)
and the Code of Practice for Victims of Crime. Investigators must ensure they have a good understanding of these, as well as criminal justice processes and their purpose, seeking support where necessary (see Taking responsibility for your professional development and Supporting the delivery of effective investigations.

Considering the bigger picture also requires a knowledge of national and force policies and procedures. Investigators should ensure they have an awareness of these. Disclosure is also an important aspect of every investigation and should be taken into consideration from the start. Effective disclosure will support a fair criminal justice system and the right to a fair trial, helping to ensure that the right people are prosecuted and convicted, thereby contributing to a safer society.

    Professional curiosity

    The exercise of professional curiosity was considered crucial by the committee to ensuring that investigation is maximised to gather the best evidence. By being professionally curious, investigators fulfil the legal obligation to pursue all reasonable lines of enquiry. It is also important when forming hypotheses to inform lines of enquiry. Professional curiosity involves maintaining an open mind, by having the capacity and willingness to explore a situation and alternative views and explanations. The need to be open-minded is also set out in the competency and values framework (CVF).

    Professional curiosity can include:

    • exploring and understanding what is happening by asking questions
    • not accepting things at face value
    • enquiring more deeply and challenging one’s own assumptions
    • thinking outside the box and being prepared to challenge conventional thinking
    • being alert to relevant material or information and exploiting digital opportunities
    • looking for, and considering, alternative explanations
    • considering a situation holistically, identifying gaps in knowledge or understanding and seeking to fill them recognising that victims of certain crimes may be unwilling to give a full account or may minimise the seriousness of an incident
    • thinking beyond past experiences
    • seeking input from others
    • seeking corroboration and testing material
    • being open to change – for example, in relation to who is the victim and who is the suspect

    Exercising professional curiosity has been translated in the following ways:

    • applying the five Ws and H framework – who, where, what, when, why and how
    • applying the ABC approach to material and evidence to ensure the collection of best evidence – Assume nothing, Believe nothing, Challenge everything

    Reflective practice and seeking input from others, such as supervisors and colleagues, may help in developing professional curiosity. Investigators may find it useful to use frameworks for reflective practice (see Making good decisions). Practical advice on encouraging professional curiosity is contained in the Vulnerability-related risks guidelines. These guidelines also outline how to recognise and respond to risk.

    Employing good communication skills is important in the exercise of professional curiosity. Key communication skills include building rapport, active listening, using a procedurally just approach (being open, respectful and transparent) and minimising judgment. Practical advice on verbal and non-verbal communication, as well as asking questions, can be found in the Initial accounts guidelines and the Vulnerability-related risks guidelines.

    Achieving best outcomes

    A component of an effective investigation is striving to achieve the best or most suitable outcome for victims and
    suspects in an incident and considering the most appropriate disposal for each case. This involves thinking holistically and considering all possible outcomes, including considering risk and safeguarding. Where appropriate, they should consider alternative evidence-based criminal justice outcomes, such as restorative justice, and should ensure due consideration is given to the appropriateness of prosecution.

    There are circumstances where it may not always be appropriate to prosecute, such as in cases where issues of exploitation and vulnerability need to be taken into account. Nonetheless, public safety issues should also be considered.

    Related authorised professional practice (APP)

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