Cambridge Crime Harm Index objective risk suspect management process

The aims of the objective risk management process are to:

• produce a quantifiable and objective-based suspect management process to reduce the risk of human error and subjectivity in the suspect management process
• accurately identify suspects who pose a high risk to the community and effectively target them for early progression and ongoing orders

The intended outcomes of the objective risk management process is to:

• reduce reoffending rates (reduced CCHI score for nominals)
• reduce crime rates overall (reduced overall CCHI score)
• reduce demand on police officer’s workload
• increase public satisfaction and trust of the police within communities
• reduce harm within communities

Cambridgeshire Constabulary identified the current suspect management process was too subjective, potentially leading to human error in risk perception and different criteria’s being used. 

Suspects who posed as a high risk to communities were not being recognised and targeted for early progression and ongoing orders including criminal behaviour orders and stalking prevention orders as a result. Continued and increased offending could persist, creating further demand on the force, and decreasing public satisfaction and trust of the police. 

Identifying the CCHI

From internal searches within the constabulary, intelligence analysts identified the CCHI (developed by the University of Cambridge’s Centre for Evidence-Based Policing) as a possible solution. The force was briefed by academics from Cambridge University about the CCHI and how it could be used to improve suspect management. The CCHI is free to use.

The CCHI calculates an objective harm index score to measure the risk a suspect holds to the community. CCHI scores range from 0 upwards, with the highest scores reaching 3000 upwards. Each score is calculated using previous offending history and incorporates:

• severity of offences
• number of offences
• frequency of offences

Each suspect’s CCHI score is updated automatically monthly.

The Cambridge Crime Harm Index (CCHI) model is published on the following webpage The Crime Harm Index — Cambridge Centre for Evidence-Based Policing Ltd. The scoring provided from the website is then utilised by Cambridgeshire Constabulary to score any suspect that is listed within crime reports as an outstanding suspect. The CCHI will then provide a set of scores, extracted from the suspects previous 3 months offending history. These scores are then totalled, providing an overall CCHI score for each offender, which updates each month to give the most accurate 3 month offending history. This ensures that the offenders which cause the highest harm to the organisation are identified via the most recent and relevant set of data.

Incorporating the CCHI into force

A meeting was held with senior analysts within the force to determine how the CCHI could be used and whether it would be beneficial. The force determined that suspect data held within Athena (the forces’ intelligence database holding all crime records) could not directly include the CCHI. This was due to the additional cost all forces using Athena would have to agree upon and pay. Data from Athena could be exported to excel via CORA (a program that exports data from Athena into an excel spreadsheet). From this, the dataset in the spreadsheet is filtered down to the suspect management table, with focus on live crime and outstanding suspects. The CCHI was then incorporated, and risk scores were sorted from highest to lowest. A VLOOKUP from the suspect management table and the CCHI scores then provided the names of the highest risk suspects for the force to focus on. 

Initial trial

An initial trial was run to determine whether the model worked. The model quickly identified a prolific outstanding suspect with a high CCHI score. This suspect has previously been missed via the subjective process despite the fact they were well known by the force. Incorporating the CCHI was deemed to be beneficial.

Proof of concept trial

A month-long trial then took place within the northern District’s criminal investigation department (CID) of Cambridgeshire Constabulary. The results a showed a reduction in the overall CCHI score for northern CID. 

Rollout

Due to this success, a six-month long trial then occurred for the entirety of Northern district policing within the force. It was then signed off for the whole of district policing within Cambridgeshire (northern and southern districts). 

Standard operating procedure for spree offenders

The trial highlighted that some areas of the force did not hold anyone with high CCHI scores, making it difficult to identify which suspects to target. In addition, spree offenders had to be identified manually, as a suspect outstanding for multiple crimes, would be recorded as multiple suspects on Athena. Therefore, for a high-risk suspect to be targeted, they must have reached a CCHI score of 1000. If there is no suspect that has reached this threshold, then spree offenders would be identified as the officer’s focus.

A policy document was then developed around the utilisation of the CCHI/spree offenders’ model.

This collective approach is automatically updated weekly, and targets 40 suspects per week across the organisation. These suspects are identified as causing the greatest harm based on either spree or risk-based scores from the CCHI.

Review for ongoing prevention orders

The force collaborates weekly with the partnership and prevention hub (who provide guidance around ongoing preventative orders), to ensure they are aware of the suspect cohort. The partnership and prevention hub then review the cohort for additional prevention orders. This allows for future offending to be reduced, even if a criminal prosecution is not possible.

Officer briefings 

A briefing slide is produced weekly, split across both northern and southern districts (20 suspects per district). This briefing is shared with the public-facing officers to ensure they are aware of the cohort of identified suspects. Should they encounter them, appropriate action is taken to bring them into custody and seek positive outcomes. This reduces further offending and harm posed to the community.

An evaluation of the impact of implanting the CCHI is ongoing and being led by Cambridgeshire Constabulary.

The evaluation consists of internally tracking the overall CCHI score for the force, which is the sum of all the risk scores calculated. This score can be tracked within localised district areas or force-wide level.

Public satisfaction surveys are planned to be implemented at a later date.

Since the implementation of the CCHI there has been:

• a 20% reduction in outstanding suspects within Cambridgeshire
• a reduction in the risk posed to communities in Cambridgeshire, indicated by a decreasing overall CCHI score
• increased knowledge and confidence for public-facing officers in identifying and dealing with high-risk suspects
• reduced demand on officer’s workload due to a more focused approach
• reduced police staff workload due to increased assistance in identifying those to target for progression plans or ongoing orders 

• Contributions from several departments (including data analysts, senior leadership teams, standards and insurance team) was vital for successful implementation. If support from one department drops, the process of utilising the CCHI becomes less efficient.
• Clear briefings for public facing officers allows maintained focus on each teams’ targets. However, if no high-risk offender has been identified, a team does not need a target.
• Those identified as high-risk may have committed lower-level offences and officers may not understand why they have been selected as a target occasionally. Support from officers In charge allows for clear rationalisation of each target and highlights the impact and offender may have if not targeted.
• Contributions from the force’s senior analysts allowed for implementation of the CCHI to be quick and easy. Using already established and managed databases prevented an increase in police staff workload and use of resources.

The importance of using both objective and subjective processes

It is important to have both an objective and subjective process to identify risk with any evidence-based policing concept. The objective process is via the CCHI, whereas the subjective process is via the identification of suspects that are causing harm via their most recent offending. For example, high-risk domestic violence perpetrators who would be identified as part of an objective crime review and highlighted as a priority suspect for progression. This then feeds into a daily management report of high-risk suspects (identified subjectively) and high priority suspects (identified objectively within the CCHI scoring). 

It is important that both are briefed to any force to ensure awarenss that data isn't fool proof and although it will frequently identify these high-risk suspects, it is important that officers are able to identify these via subjective crime reviews where risk should continually be evaluated and captured.