Case Studies

CCTV evidence study

by Mark Rowe

CCTV cameras provide evidence ‘useful’ to the police in two-thirds of the investigations where they are available, research suggests. A Nottingham Trent University (NTU) study involved analysing more than a quarter of a million crimes recorded on the railways by British Transport Police over five years.

NTU found that CCTV was available in the investigation of almost half of those crimes – 111,000 offences – and proved useful in 65 per cent of those.
When CCTV was deemed ‘useful’ by the police – when they felt it was helpful in some way to their investigation – the probability of a crime being detected rose significantly from an average 23 per cent to 48 per cent. Large variations were identified in relation to crime type and the extent to which cameras were viewed as useful. Cameras were deemed useful in 62 per cent of the 83 per cent of robbery investigations when they were available. For serious assault cases, they were useful 61 per cent of the time – available 74 per cent – and when investigating theft from a shop, cameras were useful in 53 per cent of a possible 60 per cent of cases.

They were also useful for most public order investigations in which they could be called upon – 44 per cent from a possible 52 per cent of cases.

At the other end of the scale, usefulness of cameras was particularly poor for cases of theft from motor vehicles, the researchers found – useful just 16 per cent of the time, from a possible 50 per cent. For theft of a motor vehicle, cameras were useful in fewer than half of investigations, helping police in 24 per cent of a possible 59 per cent of incidents. For theft from a person they were useful just 14 per cent of the time despite being available for 33 per cent of investigations.

Having useful CCTV was associated with significantly increased detection rates for all types of crimes, except drugs, fraud and public order offences, the study showed. The largest change was for robbery, where the probability of detecting an offence increased from 8.9 per cent without useful CCTV to 55.7 per cent with it – while for criminal damage the likelihood quadrupled from 10 per cent to 40 per cent.

Detection rates for thefts were extremely low without CCTV evidence – just 2 per cent of thefts from a person were detected without the use of cameras, the study found.

Dr Matt Ashby, a criminologist in Nottingham Trent’s School of Social Sciences, was lead researcher. He said: “This study is the first to look at both availability and usefulness of CCTV. It shows that CCTV is frequently useful in the investigation of crime and is associated with a substantial increase in the likelihood of most types of offences being solved. CCTV is clearly a powerful investigative tool, particularly for more serious crimes.

“This does not mean, however, that there should be a rush to install cameras in all types of locations. Consideration should always be given to the potential for frequent or serious crimes to occur, or whether there’s an opportunity to use cameras for multiple purposes.”

The study is in full in the European Journal of Criminal Policy and Research.

Picture by Mark Rowe; station platform, Glasgow.

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