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Investigation of fatal and serious injury road collisions

Authorised Professional Practice

This page is from APP, the official source of professional practice for policing.

First published
Written by College of Policing
Roads policing
21 mins read

The police are the lead agency for collision investigation, and have the primary duty to investigate and establish the circumstances that have led to road deaths and life changing injuries. They must discharge their responsibilities to the coroner, the wider judiciary and family members. The investigation provides an explanation to family and friends of what has happened to the deceased and/or seriously injured. It should also be used to identify preventive measures to reduce further deaths and serious injuries on the roads (see the National Police Chiefs' Council (NPCC) National Roads Policing Strategy (2022-2025)).

Forces should ensure that:

  • there is an appropriate initial response and an investigation stage
  • there is effective collision scene management
  • an effective forensic collision investigation strategy is in place
  • the investigating team have access to appropriate facilities, equipment and external expertise to perform their roles effectively
  • there are agreements with partner agencies which clarify roles and responsibilities in relation to road death investigation
  • specific roles and responsibilities are set out

An appropriate review process should be developed and implemented. Throughout this process consideration should be given to:

  • timing
  • the reviewing officer and the focus of the review
  • procedures
  • reports and subsequent action
  • disclosure

Road deaths and life-changing injuries

Road deaths and life-changing injuries from collisions are so serious that the life-long health and wellbeing of the individuals connected are drastically affected. They have a devastating impact on families, individuals and communities.

The unexpected loss of a loved one in tragic circumstances is an event from which those affected may never fully recover. The police service must recognise the scale of this impact and loss, and provide an investigative response and level of support that searches for the truth while supporting those affected in a compassionate way. It is also important to understand that road casualties may be victims of a criminal act other than being injured parties from an accident.

In the aftermath of a road death, it is understandable that the relatives and friends of the deceased may wish to visit the scene. This may be possible, but the varying nature of scenes and environmental factors mean that this should be carefully considered by those participating and this should be communicated to them. It may be acceptable, subject to the agreement of the local highway authority, to place flowers on the verge away from traffic. Many local authorities have introduced a roadside memorials/tributes policy that makes provision for families to express their grief by placing flowers or other articles. Where a local policy is in place, police officers should support the protocol as long as there is no danger to others. Placing flowers or other memorials is not practical within a motorway environment and certain other fast road environments.

Initial response

Forces must have, or have access to, an appropriate proactive, preventive and investigative road-traffic response 24/7, and be responsible for ensuring that resources are configured to meet local needs.

Upon notification of a collision involving a road death(s) or life changing injury, the following should be recorded:

  • dangers at the scene
  • name, home address and telephone number of the informant
  • first account of the informant
  • location of the scene and possible entry and egress points
  • vehicle identification
  • details of other people present at the scene
  • first description of suspect(s)

Additionally, the duty or on-call silver commander for the force area in which the collision has occurred should be informed. The duty or on-call silver commander should review the circumstances of the incident, the force’s initial response, resourcing and investigative lead as well as consider the wider force, community and reputational impact issues. It may also be necessary to inform the force gold of the incident.

Recordings of all communications, for example, telephone and Airwave, associated with the investigation should be preserved and made available to the roads policing lead collision investigator (RP lead investigator). As with any investigation, the golden hour principle and the requirement for fast-track actions apply.

Roads policing lead investigator

This role and its responsibilities represent the individual who has overall responsibility for management of the investigation. It focuses on a requirement for roads policing expertise/operational competence, and is not necessarily rank based. Those investigating fatal and serious collisions should have completed suitable learning in accordance with College of Policing standards (available via College Learn - you will need to log in).

The RP lead investigator is responsible for developing, where appropriate:

The RP lead investigator’s approach to planning an investigation should be recorded in policy files. These should be used to record strategic policy decisions, operational priorities and strategic, critical and investigative issues. RP lead investigators should make appropriate use of the national decision model.

RP lead investigators should ensure that longer-term prevention, intelligence and enforcement opportunities, with regard to wider road policing and road safety issues, are identified and shared and that local neighbourhood policing teams are engaged in the investigative support role as required.

The role of forensic collision investigator and RP lead investigator are separate, requiring different skill sets and experience. An individual should not perform both roles on a single incident.

Experience and expertise required

The table below can be used, at an early stage, to categorise the level of investigation and assist in assigning an appropriate RP lead investigator. It is essential that the RP lead investigator liaises with the Crown Prosecution Service (CPS) at the earliest opportunity where the evidence supports the likelihood of criminal proceedings.

Category A+ Assessed as likely homicide investigation or where complexity requires the deployment of a nationally registered senior investigating officer (SIO).
Category A Confirmed fatality – one or more vehicles failed to stop and/or drivers decamped or other factors are present that significantly increase the complexity of the investigation.
Category B Confirmed fatality – all drivers/riders are known or can be immediately identified.
Category C Confirmed fatality – driver/rider only killed, no third party involvement – inquest only.
Category D Confirmed fatality – driver/rider only killed, due to natural causes, may involve a third party – no inquest necessary.

Communication and community strategy

The RP lead investigator is responsible for developing a communication strategy, for example, a media strategy and/or an internal communication strategy, where needed. The police have primacy over decisions to release information or photographs about an incident and those involved.

Positive engagement with the media and using social media effectively should ensure that a fair and thorough investigation is conducted in the public eye. Personal or other sensitive information relating to key individuals involved should be protected and released only where it is necessary and prudent to do so.

Where the police have contact with the family of the victim(s) of road deaths, they should make the relatives aware of a press or social media release before it takes place. Families should be given copies of any such statements. They may also wish to contribute to the appeal for witnesses, or release pictures of the deceased.

Fast-track actions

The content of media holding statements for investigations of road deaths may include information such as:

  • the police are currently investigating a road death
  • the location of the road death
  • initial indications of the nature of the road death, for example, fail to stop
  • whether an incident room has been set up, giving the contact telephone numbers and details of appropriate websites and social media outlets
  • an initial appeal for witnesses and/or information

The communications strategy should include consideration of social media opportunities and how inaccurate rumour and reporting can be counteracted, for example, through early, definitive messages from the force’s website and social media channels.

The establishment of online tribute sites set up by family members to the deceased via social media applications are helpful in channelling information and providing opportunities to contact witnesses, develop investigative opportunities and secure antecedent information from family and friends.

The RP lead investigator will need to assess the benefits of communicating with the family, friends and the local community before deploying a family liaison officer (FLO).

Information should also be provided for traffic broadcasts. This will assist motorists and the police by diverting traffic around the site, and should be organised in liaison with Highways England and/or local authorities.

For further information see the authorised professional practice (APP) on fast-track actions.

Community tension assessment

RP lead investigators should recognise and take account of the impact a road death, life changing injuries and their investigation have on the community. The level of impact assessment and involvement will vary. In all cases the RP lead investigator should involve the local neighbourhood policing team to assist with the investigation, manage community engagement and secure a structured return to normality.

The neighbourhood policing team is able to prepare a community tension assessment and make use of community contacts to assess the impact on the local community, to disseminate key messages and collate evidential and investigative opportunities.

If necessary, the RP lead investigator may wish to use specialist diversity units and enlist the support of independent advisory groups (IAGs) at local and force level.

Some members of the community, including children, cyclists, pedestrians and motorcyclists, are especially vulnerable on the roads. A mix of prevention, intelligence and enforcement solutions may help to reduce the number of road-related deaths across these groups. Solutions represent a long-term approach and will be carried out in partnership with a number of other agencies, for example, local strategic partnerships, casualty reduction partnerships and through the preventive work of local authorities.

For further information see the:

Making the scene safe and preserving life

Making the scene safe prevents further casualties and ensures that an incident does not escalate. Following this, the condition of the victim(s) should be assessed.

Preserving life is the priority, but providing first aid and removing a victim(s) may disturb the scene and destroy evidence. Consideration should, therefore, be given to using video and photography to record the scene. In the absence of such equipment, a sketch may help.

Securing the scene

To secure the scene of a collision, police officers have the power to:

Police community support officers (PCSO) and Highways England traffic officers can also assist with securing a scene. It may also be necessary to call on the services of the local highways authority or Highways England to help with road closures and diversions. In these circumstances, existing protocols and the CLEAR guidance should be applied. See Strategic road responders agreement (National Highways, 2022).

A scene log should be started, which includes the:

  • name of the officer keeping the record
  • name of any person entering or leaving the scene
  • date and time of such entry or departure
  • reason for entry

The scene log ensures that:

  • there is no unauthorised entry to the scene(s)
  • the integrity of potential physical material is secured and preserved
  • intelligence opportunities are maximised, for example, by obtaining details of potential witnesses and/or suspects who approach the police cordon
  • contamination issues are appropriately managed

Preserving the scene

Physical material may be fragile and easily destroyed or contaminated. Staff involved in the initial response should take action to maximise the chances of recovering physical material without contaminating or destroying it. This can be achieved by taking the following steps.

  • Identify – this is a priority activity and staff should redefine scene parameters if necessary.
  • Protect – in addition to safety issues, officers should prevent further meteorological, human or animal disturbance of the scene. Protecting the scene can also be achieved by identifying a single access and exit route, complemented by identifying permissible routes within the scene.
  • Secure – methods available to secure a scene are:
    • cordons and tape
    • stationing officers at entry points with cordon control
    • blocking access by using vehicles
    • road closures and diversions
    • temporary fencing

Accurate records of all the actions taken should be maintained and reported to the RP lead investigator.

Securing material and identifying witnesses

Officers attending the scene of a collision should secure all available material to maximise investigative opportunities. Where human tissue needs to be seized during the course of the investigation and retained as evidence, the RP lead investigator should ensure that this is undertaken lawfully. Guidance on the lawful seizure, retention and disposal of human tissue can be found in the College of Policing (2019) Practice advice: The medical investigation of suspected homicide.

The early identification of witnesses and securing their initial accounts is important as people may leave the scene after the emergency services arrive. Recording the details of vehicles present, for example, index numbers of vehicles caught in queues behind cordons, to identify witnesses can help to provide accounts of people’s driving prior to the collision. These accounts can be valuable in helping to prove dangerous driving.

The details of victims and witnesses who attend hospital should be obtained, and the RP lead investigator should consider appointing a hospital liaison officer to:

  • establish what has happened, including details of drivers/riders and others present during the collision (subject to medical advice)
  • request a blood sample where there is a suspicion of alcohol and/or drug use (this should be requested at the earliest opportunity and, if applicable, prior to any blood transfusion)
  • obtain medical opinion about the victim’s condition
  • obtain details of family, friends or associates who visit the victim as they may be witnesses or sources of other information
  • consider the forensic seizure of clothing and/or property (including mobile telephones) at an early stage

Identifying the suspect(s)

Isolating any suspects and/or vehicle(s) is essential to limit cross-contamination of material where identification may be an issue. Officers who have not been involved in the initial response and/or investigation of the scene should remove suspect(s) from the scene.

Officers should breath test every driver/rider involved in a collision and should also consider whether there has been impairment through drugs use. It is strongly recommended that officers who have received drug recognition training (DRT) and field impairment testing (FIT) should be used. In addition, driver/rider fatigue should be considered as a possible cause, as should the distraction of the driver/rider. The Health and Safety Executive (HSE) should be consulted where there are concerns regarding work-related issues, for example, driver’s hours and poor company practice.

Where a driver/rider has failed to stop at the scene of a collision, the following should be considered.

  • Circulating a description of the offender and vehicle.
  • Placing a marker on the vehicle’s record, on the police national computer (PNC).
  • Searching the scene for material that may identify the vehicle or suspect.
  • Making enquiries with the registered keeper.
  • Identifying automatic number plate recognition camera opportunities and searching databases.
  • Setting up road checks under the Police and Criminal Evidence Act 1984 s 4.
  • Checking abandoned or parked vehicles.
  • Identifying the route taken.
  • Identifying and recovering footage from sources of CCTV (public, private and domestic systems) that may help to identify suspect(s) and witnesses.

Investigation stage

The RP lead investigator must begin a road death investigation by adopting the mindset of unlawful killing, until the contrary is proved substantially. This enables the RP lead investigator to maintain an open and inquisitive mind in the search for the truth, and to scale the investigation up or down in light of changing circumstances and any available or new material. Collisions that involve serious, life-changing injuries should be responded to, investigated and reported in the same way as road deaths.

Road death investigations should have a:

coroner, a pathologist and a disaster victim identification team may also be required.

The investigation should consider:

In most road death investigations, credible material is gathered at an early stage and provides a clear focus for enquiries. These cases are resolved relatively quickly. A minority of investigations are more complex, however, and may require a major incident room and a Professionalising Investigations Programme (PIP) level 3 (or above) RP lead investigator to investigate.

The collision may be declared a critical incident in some cases.

Road death investigation team

The RP lead investigator is the key decision maker in investigations and determines the structure of the investigating team. The core roles for every road death investigation include:

  • forensic collision investigator(s)
  • vehicle examiner(s)
  • FLO(s)
  • investigating officer(s)
  • exhibits officer
  • disclosure officer
  • scene manager
  • coroner’s officer
  • review officer

The RP lead investigator may also consider:

  • a police traffic management officer
  • investigators from other disciplines
  • an intelligence officer/analyst
  • a media/communications officer
  • scenes of crime officer(s) (SOCO)
  • an interview adviser
  • a toxicologist
  • a forensic specialist
  • a senior identification manager (SIM)
  • a specialist body recovery disaster victim identification (DVI) advisor
  • external specialists, for example emergency service personnel, the Driver and Vehicle Standards Agency (DVSA) and the HSE
  • partner agencies, which may provide additional support throughout the investigation, case assessment and judicial inquiry – early referral by the FLO (in agreement with the RP lead investigator) to voluntary sector and charitable organisations is important

FLOs should ensure that family members are provided with the Brake support pack, 'Information and advice for bereaved families and friends following a death on the road in England and Wales'. It should be hand delivered within 24 hours, and preferably at the time the family is informed of the death. The Brake helpline, printed on the front of the pack, should be highlighted to the recipient.

For further information see:

Forensic collision investigator

A forensic collision investigator should be used during road death investigations. If not required, the decision and rationale must be noted in the policy file.

This role may be undertaken by police officers or civilian staff specifically employed as forensic collision investigators.

This investigator:

  • identifies, preserves and records all physical material which could be relevant to the circumstances of a collision
  • ensures appropriate material and topography is photographed (supplemented by video recording if necessary)
  • digitally surveys, where appropriate, the scene and prepares scale plans and other visual representations
  • conducts, or makes arrangements for, any tests or forensic examinations in relation to reconstruction
  • reviews any witness evidence and comments accordingly
  • provides advice and guidance to the lead collision investigator
  • prepares written reports as required
  • provides ‘expert’ testimony at court, complying with the legislative requirements of the Criminal Procedure Rules and the Civil Procedure Rules

Forensic vehicle examiner

A forensic vehicle examiner should be used during road death investigations. If not required, the decision and rationale must be noted in the policy file.

This role may be undertaken by police officers or civilian staff specifically employed as forensic vehicle examiners. In cases involving large goods and passenger carrying vehicles, forces may have protocols with the DVSA to provide assistance.

The key requirements of vehicle examination include:

  • establishing the pre-collision mechanical condition of the vehicle, controls, switches and other components
  • in conjunction with the forensic collision investigator, considering the likelihood of a vehicle-related factor having caused or contributed to the collision
  • identifying and recovering forensic material (for example, mechanical components/vehicle borne electronics) from vehicles
  • recording details of the position and extent of the damage
  • identifying whether any devices have been fitted to the vehicle and to secure available electronic data from vehicle electronic control units (ECUs)
  • identifying any vehicle-related issue/design implications and identify the potential to affect the overall safety of similar vehicles
  • provide advice and guidance to the lead collision investigator
  • preparing written reports as required
  • providing ‘expert’ testimony at court complying with the legislative requirements of the Criminal Procedure Rules and the Civil Procedure Rules

Disaster victim identification team

Liaison with a SIM to work alongside the RP lead investigator should be considered at an early stage. DVI managers for scene evidence recovery (SERM), casualty bureau (CB) / Major Incident Public Portal (MIPP) (CB manager), family liaison coordinator (FLC) and police mortuary operations (PMOC) can also be appointed as necessary.

DVI teams are trained to International Criminal Police Organisation (INTERPOL) standards. When working in conjunction with roads policing personnel, they may be able to contribute important evidence to assist the investigation.

Using trained and equipped DVI personnel enables nationally and internationally approved procedures to be adhered to. They will follow the strategy set by the SIM and RP lead investigator. This process also complements the family liaison and CB process.

Where appropriate, seeking advice or support from specialist body recovery officers will provide tactical options to assist the RP lead investigator. This can improve responder wellbeing and, ultimately, the service to the public, particularly bereaved families.                                              

The RP lead investigator and SIM should also be familiar with the Joint Emergency Services Interoperability Principles (JESIP). This includes detail relating to the joint operational model and shared situational awareness – for further information, see the APP on Civil contingencies.

Collision scene management

The RP lead investigator may appoint a dedicated scene manager where there are complex or multiple scenes. The RP lead investigator should set the initial objectives for the scene examination, and develop them in liaison with the collision investigator and other specialists, where appropriate. The collision investigator is responsible for conducting scene examinations.

The RP lead investigator is responsible for setting objectives for any searches, and may liaise with a police search adviser (PolSA) to advise on the parameters of the search and scene preservation.

The RP lead investigator is also responsible for managing disruption and releasing the scene. The CLEAR guidance will aid the decision-making and policy process – see CLEAR Keeping traffic moving (National Highways, 2021). See also Strategic road responders agreement (National Highways, 2022).

Scene examination

Key objectives for conducting scene examinations include:

  • identifying, securing and recording physical outcomes relating to the collision
  • obtaining information at the scene, which may not be available later
  • identifying material to be seized for examination at a later date

Objectives should include some interpretation of what is likely to have happened. Hypotheses must be considered in cases where this is unclear or unknown.

The RP lead investigator should consider:

  • seeking relevant expertise from outside the investigation team
  • establishing a dedicated forensic management team
  • designating an exhibits officer
  • gathering post-scene material
  • recording of the scene
  • supporting information provided to the media in accordance with the communication strategy
  • supporting the presentation of evidence at court

It is essential that during a road death investigation the RP lead investigator liaises with the CPS, at an early stage, on the issue of potential vehicle seizure and retention. Vehicles may have to be retained as exhibits until the conclusion of any prosecution and any periods for appeal. See R v Beckford [1996] 1 Cr App R 94.

Recording of the scene

This can:

  • demonstrate the integrity of any material obtained from the scene
  • provide evidence of a link between scenes
  • make explicit the basis for any interpretation of the scene
  • facilitate a reinterpretation of the scene if fresh information becomes available

Appropriate methods for recording the scene can include:

  • a written record
  • formal scene plans (these can be undertaken by the collision investigator)
  • stills photography
  • video photography
  • 360 degree photography
  • aerial photography
  • virtual systems
  • surveying equipment, for example, theodolite equipment with or without global positioning systems (GPS)

Post-scene material

Material which can be gathered after the scene has been cleared includes:

  • measurements of gradients, road cambers and sight lines to help prepare scene plans
  • full mechanical vehicle examination reports
  • vehicle damage intrusion measurements, which may assist in vehicle speed estimations
  • additional photographs of vehicles and scene
  • analysis of injuries to establish points of contact with vehicles and pedestrian positions and movement
  • tachograph installations
  • material from on-board vehicle computers, collision/journey data recorders

Conducting scene examinations

The following should be examined and, where appropriate, located, measured, described and photographed.

  • The condition and operation of traffic control systems and streetlights.
  • The position of control systems within the vehicles.
  • The vehicle, to identify whether collision/journey data recorder devices (including tachographs) are fitted to the vehicle and/or any other devices which may provide information, including the engine control unit or other on-board vehicle computer (including satellite navigation).
  • The condition of vehicles and relevant street furniture and, where evidence permits, physical marks should be attributed to the vehicle or object which made them.
  • Contact marks, vehicle tyre marks and corresponding skid marks.
  • Debris.
  • Bodies.
  • Post-collision position of vehicles.

The introduction of advanced scene examination technologies such as laser scanning can significantly improve the detail and quality of evidence.

Recovery and identification of the deceased

Fatal and serious injury collisions often result in complex scenes requiring specialist advice in relation to the deceased and/or fragmented body parts. This could also include recovery and retention of personal, technical, and evidential property, especially where the identity of the deceased is challenging due to fire, disruption of the body or in any multiple fatality road traffic collision (RTC). The advice of these specialist police teams should be considered at an early stage. 

The disaster victim identification (DVI) process within a road death investigation includes the recovery, potential identification and reconciliation of human remains. 

Every incident is different and may present unique challenges regarding formal identification of victims. When deploying teams, the scale and complexity of the incident should be considered, and the proportionality of the response tailored to meet the needs of the RP lead investigator/SIM strategy. This approach also complies with the recommendations set out by Lord Justice Clarke on the handling of victim identification following transport incidents involving fatality, and supports the Charter for Families Bereaved through Public Tragedy.

Collision statistics

STATS 20 provides instructions on completing road accident reports and can be found on GOV.UK.

Managing disruption and releasing the scene

The RP lead investigator should ensure that road closures are appropriate and proportionate to the needs of the investigation. Forces should adhere to the CLEAR guidance in discharging this responsibility. See CLEAR Keeping traffic moving (National Highways, 2021).

To reduce disruption, RP lead investigators should determine the sequence of material collection to facilitate the early release of some, or all, of the road. Other options for reducing disruption include:

  • appointing a diversion manager to assist the highways authority
  • using strategic variable message signs, media broadcasts and other forms of communication to advise motorists of diversions
  • early access by agents who will assist in restoring the scene
  • arranging for vehicles and equipment to be marshalled near the scene and then escorted by the police or a Highways England traffic officer

RP lead investigators should not release a scene until they are satisfied that it has been fully exploited for investigative opportunities. Advancing the investigation takes precedence over the need to reopen roads.

Forensic collision investigation strategy

The RP lead investigator is responsible for developing and implementing this strategy. RP lead investigators should consider:

  • human, vehicle and environmental factors
  • recording the scene
  • post-scene considerations

The strategy provides:

  • clarification of circumstances
  • clarification of a sequence of events
  • testing hypotheses, for example, did the road surface contribute to the collision?
  • prioritising lines of enquiry
  • corroboration
  • interview material
  • identification and/or implication of offenders
  • elimination strategy (trace/interview/eliminate)
  • prioritisation of laboratory submissions
  • for linking multiple scenes and incidents

Road policing intelligence strategy

The RP lead investigator should be aware of the potential for information and intelligence to promote new lines of enquiry. They should develop a specific intelligence strategy where appropriate, which may include:

  • information sources
  • the use of open and closed social media sources as investigative, intelligence and communication opportunities
  • information and intelligence evaluation
  • covert policing techniques
  • analytical support
  • analytical products

The use of social media sources

Social media, for example the internet, social networking sites and real-time information sharing capabilities have created an operating environment for police officers where information (both accurate and inaccurate) is readily available. It is not possible to fully prevent this effect but working with social media positively offers the best opportunity for the police to undertake investigations, share information and support victims.

Those seeking information are likely to take account of police websites and their linked social media feeds, for example Facebook and Twitter. RP lead investigators should consider releasing information through force and social media channels promptly to establish a position that the information provided is the accurate and definitive message.

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