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Habitual knife carrier index

Combines police crime and intelligence data with known risk factors associated with serious violence, to identify individuals most at risk of current or future involvement in knife crime.

First published

Key details

Does it work?
Untested – new or innovative
Crime prevention
Violence (other)

Simon Yates

Email address
South East
Community safety partnership
Health services
Local authority
Stage of practice
The practice is implemented.
Start date
Scale of initiative
Target group
Children and young people


The overall aim is to identify individuals currently involved in or at risk of becoming involved in knife crime. Preventative and diversionary interventions are developed and delivered in partnership with other key agencies. These are targeted at individuals identified as at greatest risk, to divert them from future involvement with knife crime.  

Intended outcome

For participating children


  • Be engaged in evidence-based programmes that divert from knife crime activity.

  • Engage or re-engage in positive, prosocial behaviour and activities. 

  • Reduction in risk of involvement in knife crime. 

  • Increased engagement with education. 

  • Increase in self-efficacy and resilience. 

  • Improvements in self-esteem and confidence. 

  • Parents and carers have a better understanding of risks and how to protect their children. 

  • A reduction in cohort’s risk of involvement in violence, vulnerability and exploitation. 


  • Reduction in number of exclusions. 

  • Improved school attendance or engagement in education. 

  • Reduction in new offences. 

  • Improved engagement with mental health and emotional wellbeing services where appropriate. 

For partner organisations


  • Increased knowledge of and confidence in dealing with habitual knife carriers effectively. 

  • Increased understanding of adverse childhood experiences (ACEs) and a trauma-informed approach to tackle the root causes of serious violent crime. 

  • Increased understanding of local issues and partnership responses. 

  • Increase in resilience and involvement, from all community organisations, in helping to reduce knife crime. 

  • We expect to see improved operational effectiveness and a change in current approaches.  


  • Reduction in number of new offences. 

  • Reduction in referral to Multi-agency Child Exploitation (MACE). 

  • Reduction in possession of weapons. 

  • Increased sharing of data and intelligence. 

  • The use of contextual safeguarding assessments and the focus on partnership working to reduce local habitual knife carrying problems in this project will help move professionals away from their well-established single agency responses. This will be evidence by a future move towards a much more contextually informed response across the local partnership.


Sussex Police started by agreeing a force definition of a habitual knife carrier (HKC). This is defined as either of the following.

  • Any individual recorded in force data as a suspect or offender in at least two incidents’ involving knife crime or possession of weapons in a public place (excluding domestic related offences) – with at least one of the offences occurring in the last 12 months.
  • Recorded in force intelligence data as linked to two or more reports involving knives or other weapons within the last six months. 

We included individuals who met this criteria on the HKC index. We also included data on any lifestyle factors known to be risk factors for serious violence. For example, drug use, county lines activity or mental health concerns. Force analysts use this data to assess the level of risk for each individual in terms of likely risk of current or future involvement in knife crime.  

We discuss individuals identified as at high risk at a multi-agency meeting to agree and action an appropriate response. These meetings include the police and relevant partners, such as, the community safety partnerships youth offending team and children’s services.

We update the HKC index quarterly. Two intelligence development officers (IDOs) and two intelligence analysts are attached to the programme. They are responsible for creating, updating and monitoring the index. 

Overall impact

There has not yet been a formal evaluation of the HKC index.  

However, in 2021 the force received additional funding from the Home Office Science, Technology and Research (STAR) function. This was to develop a multi-agency response to support young people identified as being at risk of involvement in knife crime.

Early analysis from this project was reported in October 2022. Over a 12-month period, there was a 57% reduction in the number of weapon possession offences involving the STAR project cohort following their engagement. Most of those targeted by the STAR project had been identified using the HKC index. 

Analysis of police data on the core group of 19 HKCs adopted as part of the STAR Project in 2021/2022 and the impact on their police interaction 12 months later
Police metrics 1 April to 24 September 2022 Difference (+/-) 1 April to 24 September 2021 (pre-STAR project)
Number of nominals coming to police attention 14 -26.3% (-5) 19
Number of police incidents and crime 88 -62.2% (-145) 233
Possession of weapon offences 1 -92.3% (-12) 13
Home Office Crime Severity Score 12,506 -61.9% (-20,330) 32,836
SCARF submissions (child to notice form) 21 -76.1% (-67) 88
Home Office Economic and Social Cost of Crime measure - police cost (£) £32,010 -55.9% (-£40,620) £72,630
Home Office Economic and Social Cost of Crime measure - total cost of crime (£) £304,560 -52.7% (-£340,710) £645,270

There is an estimated cost-benefit saving of £2.27 for every £1 spent by the STAR project on this group. This figure is based on the calculated saving of associated crime by the group using the Home Office Cost of Crime measure balanced against the £150,000 STAR funding allocation.


Sussex Police highlight the following considerations for the HKC index approach.  

  • A thorough and ongoing review of equality and data protection considerations is important to ensure that the tool is used proportionately, and that data protection principles and legislation are fully applied. Individuals listed on the index should be routinely and systematically reviewed to ensure it is kept up to date. 
  • The HKC index aims to identify individuals who are most at risk of involvement with knife crime. Establishing effective partnership working with multiple agencies to share intelligence and better target resources is critical to ensure that those individuals identified through the HKC index receive targeted support to help reduce their future involvement in violence and knife crime.     
  • Sufficient resource needs to be allocated to support the development and use of the HKC index across the force, at both an operational and strategic level. Sussex police are considering how to automate elements of the HKC index to reduce the demand on analysts.

Best available evidence

Currently, the crime reduction toolkit does not include any best-available evidence on an intervention similar to the HKC index. See Knife crime: a problem-solving guide for practical and evidence-informed advice on how to reduce local knife crime.


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Disclaimer: The views, information or opinions expressed in this shared practice example are the author's own and do not necessarily reflect the official policy or views of the College of Policing or the organisations involved.

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