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Forensic marking to deter repeat victimisation related to domestic abuse and sexual offences

Forensic marking to deter perpetrators from repeat offending using forensic marking of moveable items and doorways, panic alarms, and forensic sprays or greases.

First published

Key details

Does it work?
Offender management
Violence against women and girls
Vulnerability and safeguarding

Lee Berry

Email address
North West
Local authority
Stage of practice
The practice is at a pilot stage.
Start date
Scale of initiative
Target group
Children and young people


The aim of forensic marking is to:

  • deter offences from occurring
  • improve trust, confidence and satisfaction in policing
  • provide evidence to help bring perpetrators to justice (bringing forensic marking into the evidential chain)

Intended outcome

The intended outcomes of this initiative are:

  • reductions in incidents of domestic abuse, stalking, voyeurism, exposure, rape and sexual offences
  • reductions in repeat victimisation
  • deterrence of repeat victimisation, as perpetrators are warned that the victim has been protected
  • reduced incidents of police reported crimes
  • improvements in victim trust, confidence and satisfaction with the police

The initiative achieves this through:

  • target-hardening the victim
  • ensuring that the perpetrator is aware through warnings
  • educating officers and staff working in that area of the initiative


This initiative initially started with a pilot funded by the South Yorkshire Violence Reduction Unit (VRU). Views about the proposed initiative were sought from local authority domestic abuse leads and from a survivor of domestic abuse. Their views and experiences helped to shape the approach.

Victims are identified as requiring protection either through police investigations or partner engagement through multi-agency risk assessment conference (MARAC) processes.

The level of protection offered to victims varies, based on risk and perpetrator behaviour. An assessment is made as to the perpetrator risk and likelihood of reoffending. This assessment involves:

  • an assessment by a detective sergeant or detective inspector
  • conversations with the victim

The victim is made aware of the different available protective measures. These conversations help officers to identify which tactics may be the most suitable for the particular perpetrator. These conversations also ensure that victim needs are taken into account.

If the risk of further victimisation is assessed as low, a forensic home protection kit can be used to help reassure the victim. The kit includes stickers that are displayed in windows to clearly state that the property is protected by forensic marking – in this case, SmartWater. Items are also marked within the property with a unique forensic solution to help prevent theft or prove ownership at a later date.

If the risk assessment considers that there is the likelihood of re-victimisation, additional protective measures include the following.

  1. The issuing of a handheld forensic spray. This spray can be carried by the victim around their property or while out in public. The canister sprays a directional forensic solution with a coverage of up to 10 metres in distance.
  2. Forensic greases can also be used to mark door handles or window frames. If touched by the perpetrator, they will then be forensically linked to where the grease was deployed.
  3. Finally, where the risk of repeat victimisation is high and where potential harm caused is assessed as high, a domestic abuse spray system can be used. This unit is a multifunctional forensic spray unit, which also activates a panic alarm to the police communications centre and sounds a loud audible alarm.

With each tactic used, the perpetrator must be warned that the victim is protected. This increases the deterrence aspect of the initiative. The messaging must be clear enough to deter, without informing the perpetrator exactly how the victim is protected.

To ensure consistency and proportionality, detective inspector authority is required for each level of protection.

Although not a central element of the initiative, forensic marking can be used to reinforce bail conditions, domestic violence protection notices and orders, and other court orders.

The approach also strengthens protective measures and presents opportunities for introducing evidence-led prosecutions, by linking a perpetrator to a location or person.


Evaluations have been conducted by three police forces and academics at Sheffield Hallam University. The evaluations indicate the initiative is having a positive impact.

For the police evaluation, three forces surveyed 104 domestic abuse victims for their views on forensic marking. The results showed that:

  • 92% would recommend the forensic marking
  • 84% state it has had a positive impact on them
  • 77% state more confidence in the police
  • 78% say they feel safer
  • 74% say they have more trust in the police
  • 63% self-report a decrease in incidents

Before and after quantitative data was also taken from 43 victims. They reported a:

  • 69% reduction in reported incidents considering pre- and post- protection
  • 94% reduction in harm (using the Cambridge Crime Harm Index) in South Yorkshire Police
  • 71% reduction in harm (using the Cambridge Crime Harm Index) in West Yorkshire Police

Cost-benefit analysis

  • West Yorkshire Police estimates that a total spend of £3,683,664 has been avoided. This calculation is based on The economic and social costs of domestic abuse report (Home Office, 2019) unit cost of a domestic abuse incident and across all service providers.
  • Specifically for West Yorkshire Police, approximately a £69,660 spend has been avoided from a 69% reduction in reported crimes. This 69% reduction equates to 108 fewer domestic abuse crimes.
  • The cost of protection through forensic marking is approximately one tenth of the response to a DA crime. This is also estimated using CSEW data (based on the calculation of £645 per response to each domestic abuse crime and considering a level of protection equivalent with a medium risk domestic case).
  • For a high-risk case of domestic abuse, a victim could be protected (inclusive of officer time) for approximately four to five months for the cost of a police response to one domestic abuse crime. This cost includes the use of a domestic abuse spray system, a SmartTag canister and home protection kit as part of the forensic marking.

Overall impact

Sheffield Hallam University conducted five interviews with victims in addition to reviewing the data collected from the force evaluation. Their findings suggested that:

  • the offenders’ main aim (from a victim’s perspective) is to cause mental distress
  • SmartWater offers reassurance and confidence
  • many offenders are deterred by knowing the victim has SmartWater
  • forensic marking gives victims more confidence to testify and offers proof of domestic abuse not previously available
  • forensic marking helps build positive relationships with the police and is a relatively easy way to help victims feel they are taken seriously

This project won a Tilley Award in the Investigation category in 2022.


Challenges to date seem to be consistent across the forces involved in the initiative. These challenges include forces:

  • struggling against other demands to invest resource in safeguarding after or during an investigation
  • being able to shift towards a perpetrator-focused approach


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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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