Evidence-based guidelines on effective investigations – improving the application of the investigative mindset

This project is a rapid evidence assessment (REA) of the effective use of an investigative mindset.

Key details

Lead institution
Principal researcher(s)
Fiona McLean
Police region
West Midlands
Collaboration and partnership

The University of Portsmouth

Level of research
Professional/work based
Project start date
Date due for completion

Research context

Aims and objectives

College of Policing practice guidelines are developed and agreed by an independently chaired committee, made up of practitioners, subject matter experts and academics and are based on the best available evidence.

To develop guidelines the College carries out a rapid evidence assessment (REA) of the research literature and gathers practice evidence from officers and staff. The REA is undertaken to identify relevant evidence to be used by the Committee to inform guideline development.

The overall focus of these guidelines is on how best to ensure the application of an investigative mindset throughout an investigation. ‘Investigative mindset’ is a term used to describe a systematic approach to gathering and assessing material, underpinning an effective investigation (see section 5.3 of ACPO Core Investigative Doctrine (2005:61)).

As well as setting out the components that make a good investigative mindset, the guidelines will focus on how to support its effective application, including whether there are any tools or tactics that can be used to mitigate barriers to taking a systematic approach. The processes within an investigation cover (but are not limited to):

  • planning
  • gathering material (organising, examining, collating, recording and evaluating)
  • hypothesis development
  • testing and interpretation

The guideline will also support investigative capability among investigators, by exploring factors that can have an impact on the effective application of the investigative mindset. These are varied and may include: 

  • types of bias 
  • working rules (mental shortcuts) 
  • psychological wellbeing, including trauma and tiredness
  • adversarial culture
  • situational factors (for example, supervision, prioritisation, time and media pressure, social media and the use of technology)

The REA will therefore focus on the following questions.

  1. What is an effective investigative mindset?
  2. What factors support or hinder the effective application of an investigative mindset?
  3. What tools, resources or approaches could support or promote the application of an investigative mindset?


The College conducted a thematic analysis of recurring issues facing policing to help understand where to set national standards to drive improvement activity. This work identified a number of perennial issues facing the service, one of which related to limitations in investigative capability and issues with the collection, use and disclosure of evidence.

Within investigation, a number of specific issues have been identified, including missed opportunities to collect evidence at the scene, missing lines of enquiry, poor-quality case files and a lack of understanding of the court process.

College of Policing research on disclosure also suggests that issues with disclosure are underpinned by problems with investigations more generally, including a lack of understanding of reasonable lines of enquiry, a lack of understanding of the independent role of the investigator, and prosecution bias.

The current low charge rate, which has been on a continuing downward trend since the year ending March 2015, also points to a potential lack of experience in investigation and experience in case-file building to increase. These issues and the work outlined above suggest that there would be benefit derived from developing national guidance on the effective application of the investigative mindset.

Research methodology

An REA uses transparent, structured and systematic processes to search for, screen and synthesise research on a particular topic. An REA is not an exhaustive summary of the literature as limits are placed on the review process in order to deliver results rapidly. However, the systematic and transparent nature of the REA processes help to reduce bias and enable others to replicate the review.

The topic is scoped and inclusion criteria are developed around which studies should be included in the searches. Keywords relating to these criteria are drafted and key academic databases are searched for relevant literature. Study titles and abstracts are screened and those that don’t meet the inclusion criteria are excluded.

The full texts of eligible papers are screened using more stringent inclusion criteria, and key information is extracted from these papers including methods, population and findings. These papers are then assessed for quality and relevance to the research questions, and information is synthesised into evidence tables and summaries to inform the guideline committee.

Interim reports or publications

Effective investigations: Improving the application of the investigative mindset; Scope of practice guidelines; April 2021

Was this page useful?

Do not provide personal information such as your name or email address in the feedback form. Read our privacy policy for more information on how we use this data

What is the reason for your answer?
I couldn't find what I was looking for
The information wasn't relevant to me
The information is too complicated