SURVEILLANCE of public places, such as town centres, stations, car parks and housing estates, using closed-circuit television (CCTV) is increasingly commonplace.
The UK is first in the global league table for the ratio of cameras to people, with estimations ranging from a staggering one camera for every five people to one in 12.
The effect of CCTV cameras on the prevention of crime is difficult to measure, and recent reports have questioned their value; however, the evidential value of CCTV footage is becoming increasingly valuable. ‘Facial mapping’ experts have been called on to assist with person identification and to secure convictions with the use of CCTV imagery for the past two decades.
The scientific technique allows for any major similarities or differences between two faces to be exposed by examining the relative size and locations of features (facial geometry) and the shape, form and detail of each feature (facial morphology). Significant differences between two faces will allow the suspect to be eliminated. In the absence of such differences, the significance of any observable similarities will be assessed with reference to a five-level sameness scale.
The conclusion reached reflects the strength to which the CCTV evidence supports the contention that two individuals are, in fact, one and the same.
Facial mapping continues to be a useful aid to prosecution and defence agents throughout the UK.
However, criminals are becoming increasingly aware that their deviant actions are likely to be captured on camera, and careful measures are often taken to disguise facial appearance.
This ultimately limits the extent to which objective facial comparison techniques can be applied.
However, it is not just ‘faces’ that commit crimes; criminals wear clothing, drive vehicles and do not necessarily disguise themselves before or after a crime takes place.
Whereas at one time the focus of CCTV interpretation centred solely on the facial appearance of perpetrators, it is now becoming common practice for instruction to be given for professionals to assess these additional aspects of the imagery.
This increased diversity in the use of CCTV imagery has contributed to the expansion of the Facial Verification Bureau (FVB), which offers an independent imagery analysis service.
When the bureau was established in 2001 the majority of cases involved facial image comparisons; this now accounts for approximately 50% of cases, with the remainder involving vehicle identifications/comparisons, height calculations, clothing analysis and general interpretations. Here is an insight into each of these specific areas:
Vehicle identifications – The make and model of vehicles captured by CCTV can be determined even from relatively poor quality footage. The size and variance of the styling features on vehicles allow for identifications with reference to a comprehensive vehicle library. Reconstructions with seized vehicles and the presence of distinguishing features can provide additional evidence towards two vehicles being one and the same.
Height calculations – The height of a crime perpetrator can be determined through the use of perspective projection and superimposition techniques.
This can provide additional support towards identity or allow for elimination of a suspect. Height calculations can be used in instances where the face is not visible or in addition to a facial image comparison.
Clothing comparisons – This can involve comparisons between clothing worn by the crime perpetrator and a seized item or comparisons throughout different scenes to assess continuity. Conclusions can be made towards two items being of the same brand/styling or, in the instance of unique features (eg stains, rips, etc), towards them being one and the same item.
Mapping of movement – This technique involves the breakdown of individual frames to clarify events and actions when the specific details are of importance, eg how many times does the criminal strike the victim?
What weapon are they holding?
Assessment of continuity – It is often necessary to track the presence of an individual or a group of people throughout several locations. This may involve the creation of an annotated story board to clarify events and for effective viewing in court; additionally, facial image comparisons, clothing comparisons and height calculations can all be combined to assess the likelihood for this continuity.
For example, the crime perpetrator(s) may have been wearing disguise but were they captured on CCTV footage before or after the incident? Or were they involved in a reconnaissance?
By exploring all these options when presented with crime scene footage, expert imagery analysts from the Facial Verification Bureau can assist in ensuring that CCTV evidence is utilised to its full potential.
Importantly, the extent to which CCTV can assist in criminal investigations is also dependent on the police officers and solicitors involved in the case. It is crucial that all the relevant CCTV footage is recovered in its original format at the start of an investigation and that all parties have access to this material.
The rapid progression from analogue footage to digital footage has resulted in hundreds of systems producing imagery that requires different viewing software. Officers are also faced with the problem of obtaining footage from the systems as many don’t have the facility to download the digital footage in its original format. Instead, it is downloaded onto an analogue video tape. This will result in a deterioration in the quality of the imagery and hence a reduction in the detail which is vital when trying to secure a conviction.
Evidence provided by the FVB has been crucial to the successful completion of many cases throughout the UK since 2001. In the past, not only has the bureau’s evidence been influential in securing convictions but it has helped to prevent miscarriages of justice.
On many occasions it has resulted in changes of plea, saving significant amounts in terms of court time and expenditure.
The FVB is headed by Dr Leslie Bowie, CEng, MIET, who has over 16 years experience in the production and delivery of imagery analysis evidence.
The bureau has a team of dedicated analysts working out of offices in Nottingham and Stirling.
Following all enquiries, the FVB provides a free consultation to assess the quality of the evidence before proceeding with any form of analysis.
For more information, contact Elaine Woods in Stirling (01786 446480) or Orly Golding in Nottingham (0115 977 6927). Alternatively, visit the website at www.abmfvb.co.uk for a breakdown of the company’s services.