How Might CCTV Help Crime Investigations?


Before turning to the research questions addressed in this study, it is necessary to consider exactly how CCTV might provide useful evidence in a criminal investigation. A criminal investigation can be thought of as a series of questions: who was involved in an incident, where did it happen, what happened, when did it happen, why did it happen and how were any offences committed, known as the ‘5WH’ investigation model (Cook et al. 2016; Stelfox 2009). CCTV may be useful in answering at least two of these questions: what happened and who was involved (La Vigne et al. 2011). 

A good-quality recording could potentially allow investigators to watch an entire incident unfold in detail, providing information about the sequence of events, the methods used and the entry and exit routes taken by the offender. Even if this is not possible, CCTV may be useful in corroborating or refuting other evidence of what happened, such as witness testimony (College of Policing 2014). Recordings may also provide information that investigators can use to contextualise other evidence (Levesley and Martin 2005).

CCTV may assist in identifying who was involved in a crime either directly, as when a suspect is recognised by someone viewing the recording, or indirectly, such as when the recording shows a suspect touching a surface from which police are then able to recover forensic evidence (Association of Chief Police Officers 2011). Images can also be used to identify potential witnesses (La Vigne et al. 2011, p 27). CCTV may be less useful in answering some of the other 5WH questions. For example, even a good-quality recording may shed little light on why a crime was committed.

In order for CCTV to be useful in answering investigative questions, certain circumstances are required. There are few legal restrictions on the ability of police officers to use CCTV recordings of public places during investigations. In the UK, for example, operators of camera systems can provide recordings to the police without a warrant (Information Commissioner’s Office 2015). In the United States (US) a similar system operates, as long as the recording is of a place in which people do not have a reasonable expectation of privacy (Chace 2001). As such, the limiting factors on the use of CCTV are likely to take other forms.

Figure 1 summarises the process by which these circumstances may come about, broken down into three stages. In the first stage, CCTV evidence is not available, either because the police have not taken steps to obtain it or because no recording exists for technical reasons. In the second stage, a CCTV recording is available but—perhaps because of the recording quality—is not useful to the investigation. In the final stage, a recording is both available and useful to the investigation.

The present study aimed to explore the usefulness of CCTV for crime investigation by examining the stages in this process. Specifically, two research questions were addressed:

  1. How often do CCTV cameras provide useful evidence in criminal investigations, and how does this vary for different types of crime?
  2. In what circumstances is CCTV most likely to be useful in criminal investigations?

It might be thought that CCTV is useful in a case only if it leads to a suspect being convicted. However, this approach presents at least two problems. Firstly, it would require a potentially unreliable counterfactual test of the weight of evidence that would have been available in a particular case in the absence of CCTV recordings. Secondly, it ignores the potential value of video recordings in allowing officers to eliminate a suspect from their enquiries, or to identify where a person has made a false report of crime.

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