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Habitual knife carrier index – Sussex Police

Targeting multi-agency interventions to divert individuals from current or future involvement in knife crime.

First published


The habitual knife carrier (HKC) was developed as part of Sussex Police’s response to preventing knife crime and serious violence.

The HKC index combines police knife crime and knife-related intelligence data with known lifestyle factors associated with serious violence, such as drug use or involvement in gangs. Individuals are assessed in terms of their likely involvement in knife crime, based on knife intelligence data and associated lifestyle factors.

Its purpose is to identify individuals currently involved in or at risk of becoming involved in knife-related offences. This can be used to better target multi-agency interventions and support services to divert the individuals from current or future involvement in crime.

The index is refreshed quarterly to ensure that individuals are added and removed in a standardised and timely manner. There were 202 individuals on the index in October 2022 and 66 (33%) were assessed as high risk.


In 2019, Sussex was identified by the Home Office as one of 18 forces across England and Wales worst affected by serious violence, including knife crime offences. 

To address this problem Sussex Police prioritised work to provide a more targeted, prevention-focused response to those associated with knife crime. They developed the HKC index to identify those involved or linked to knife crime and serious violence. They received funding from the Home Office which helped them to establish a violence reduction unit (VRU) to help tackle and prevent serious violence.

Additionally, in 2021 they developed a multi-agency approach to support young people identified through the HKC index, as well as their known associates. They received funding from the Home Office Science, Technology and Research (STAR) fund to support this.

The overall aim of this holistic approach is to better identify those at risk of becoming involved in knife crime and to use this information to develop and target multi-agency responses to divert them from criminal activity.


Habitual knife carrier index

There were three key stages in the development of the HKC index.

Stage one – defining the scope

Sussex Police extended the existing Mayor's Office for Policing and Crime (MOPAC) definition of a HKC that was based on crime data to also include intelligence reports relating to knives.

Stage two – compiling force data

Local crime data was collated on any individuals meeting the force’s HKC definition. Wider intelligence data linked to each individual – such as previous criminal activity or lifestyle factors such as drug use – was also included.

Stage three – developing risk assessment

Data on an individual’s knife-related criminality and intelligence alone was not considered sufficient to identify likely risk of future involvement in knife crime. To better inform an assessment of risk, the force reviewed existing evidence on risk factors associated with homicide and serious violence. This was used to compile a set of factors that could be identified from the force’s internal crime data (Home Office Serious Violence Strategy, April 2018) and an Early Intervention Foundation report on Preventing gang and youth violence (2015)). These informed the development of 12 lifestyle questions that could be used to identify levels of likely risk. These are as follows.

  1. Does the subject use weapons for criminal facilitation?
  2. Is the subject known for violence?
  3. Has the subject ever made threats of violence to another?
  4. Is the subject a domestic abuser?
  5. Does the subject have a weapon fixation?
  6. Is the subject involved with drug use or supply?
  7. Is the subject involved in county lines?
  8. Is the subject part of a gang or peer group?
  9. Is the subject involved with anti-social behaviour?
  10. Is the subject aged under 25 years old?
  11. Is the subject a regular missing person (MISPER)?
  12. Does the subject have known mental health problems or other vulnerabilities?

These lifestyle factors are then considered alongside crime data to assess an individual’s overall risk of current or future involvement in knife crime. 

Finally, data from the Office for National Statistics (ONS) Crime Severity Score was also added to the index. This was used to measure harm and provides an additional measure to assess the seriousness and context of the HKC’s offending.

HKC index logic model


Sussex police was identified in 2019 as one of 18 forces who were most affected by knife crime offences.

Response – data and research
  • The HKC index was informed by crime records of those who had been involved in knife crime-related offences.
  • Sussex Police extended the index to include lifestyle factors identified as drivers of homicide and serious violence.
Response – engagement and diversion
  • Once high-risk individuals are identified on the HKC index, partner agencies engage with them to support their needs and divert them away from criminal behaviour.
Response – resourcing
  • Intelligence analysts assess lifestyle factors that feed into the index.
  • Intelligence development officers share the data from the HKC internally with relevant policing teams and with external partners.
  • Number of individuals identified on the HKC index.
  • Number of individuals engaged with partner agencies for support.
  • Instances of intelligence shared between Sussex Police and partner agencies.
  • Number of partners or agencies involved in partnership working.
  • Reductions in knife or weapon possession offences.

  • Reduction in serious violence involving knives.

  • Increase in positive outcome rate for serious violence crimes.

  • Improved multi-agency and partnership working.

  • Increased focused targeting of police resources.


How the HKC index works

Each quarter, data that meets the following HKC definition is collated to create a single index of individuals. 

  • Police records of those who are 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.
  • Force intelligence data of individuals linked to two or more reports involving knives or other weapons within the last six months.

This dataset is then matched with:

  • intelligence data on relevant lifestyle factors
  • data from social services that includes information on adverse child experiences (ACEs), mental health, drug dependency and education – this information is shared in contextual safeguarding meetings
  • data from the ONS Crime Severity Score dataset

Combining data from multiple sources into a single index allows a deeper understanding of an individual’s risk based on crime and wider lifestyle factors.

There are two dedicated operational safety intelligence development officers (IDOs) and two intelligence analysts working on the HKC index. The IDOs assess each of the HKCs on the index against the 12 risk factors. This data is used to make an overall assessment for each individual, which is passed on to relevant persons and departments. 

Individuals are then considered in terms of their potential risk of being involved in knife crime. This information is used to inform decisions about how resources are targeted to support and divert them from current or likely future involvement in knife crime.

The IDOs share the data from the index internally to relevant policing teams – for example, neighbourhood policing teams, missing person teams, integrated offender management teams and external partners. The IDOs can also raise people of interest at the district hub intelligence meetings, which take place every two weeks.

Data sharing agreements have been developed that are compliant with current data protection principles and legislation. This allows the names of higher risk individuals identified on the HKC index to be shared with external partners. These include youth offending teams, children’s services and the probation service. These agencies support the provision of tailored safeguarding interventions to help prevent harm to the individual, or to prevent them from causing harm to others.

The Violence Reduction Partnership Unit (VRPU) meeting provides an opportunity for these organisations to agree a multi-agency, targeted response to those individuals identified as higher risk on the index.

Each area of Sussex receives the updated HKC index quarterly and uses this data to inform how resources are managed and targeted.

Currently, young people in East Sussex who are high risk on the HKC index and willing to engage work with partner agencies through the STAR project. Partners work together to develop support packages based on individual needs. For individuals that don’t engage, the force uses a contextual assessment to target outreach work, schools and other activities, including peer interventions.

Individuals who are categorised as medium risk are discussed in monthly intelligence hub meetings where decisions are made about how best to manage them, based on their individual needs. Individuals who are categorised as low risk are monitored for any change in risk.

Enablers for implementation

Ensuring right resources

The Home Office fund enabled Sussex to pause and consider how they will address the issue of knife crime. The funding allowed the development of the index, which helps focus police resources in supporting individuals identified as at risk, to divert them from involvement in serious violence and knife carrying.

Specialist staff skills

The IDOs are key to updating and maintaining the HKC index. Intelligence is fed into the HKC index from different sources and the IDOs manually input and combine this data, taking into account individual lifestyle factors. Sussex Police provided funding for five specialist intelligence analysts to undertake training on targeting serious violence, provided by an external policing research consultancy.

Effective partnership working

Sussex Police work closely with partner agencies, including social services. When a young person or child has been identified on the HKC index, there are established structures and processes in place that allow agencies to work together to provide a response that is tailored to the individual’s needs. Established data sharing processes between agencies has enabled better identification and targeting of support.

Outcomes and impact

The overall aim of the HKC index is to more accurately identify those currently involved in or at risk of future involvement in knife crime. Developing a clearer understanding of those at risk of knife carrying informs decisions about how to better target resources to prevent homicide or serious violence.

The HKC index has not been subject to an external review or testing, although an evaluation is planned.

However, the index has been used to identify which individuals are offered support through the STAR project. Early analysis and data from October 2022 shows that 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.

Learning and recommendations

Sussex Police highlights 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 – and removed when necessary – 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 is considering how elements of the HKC index could be automated to reduce the demand on analysts.

About the project

This practice example has been compiled using Smarter System principles. This involves experienced practitioners from the National Police Chiefs' Council (NPCC), College of Policing, His Majesty's Inspectorate of Constabulary and Fire & Rescue Services (HMICFRS), in consultation with the Independent Office for Police Conduct (IOPC), working together to identify and review policing interventions and activity.

Key features are presented in a format that can be considered and where appropriate, implemented by other forces as they address the crime challenges they face. These examples are referred to as smarter practice. 

Read more smarter practice examples

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