CCTV cameras provide evidence 'useful' to the police in two-thirds of the investigations in which they are available new research suggests.
The Nottingham Trent University study, involved analysing more than a quarter of a million crimes recorded along the railway network by British Transport Police over a five-year period.
It was found that CCTV was available in the investigation of almost half of those crimes – 111,000 offences – and proved useful in 65 percent of those cases.
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 percent to 48 percent.
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 percent of the 83 percent of robbery investigations in which they were available. For serious assault cases, they were useful 61 percent of the time – available 74 percent - and when investigating theft from a shop, cameras were useful in 53 percent of a possible 60 percent of cases.
They were also useful for most public order investigations in which they could be called upon – 44 percent from a possible 52 percent 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 percent of the time, from a possible 50 percent. For theft of a motor vehicle, cameras were useful in fewer than half of investigations, helping police in 24 percent of a possible 59 percent of incidents.
For theft from a person they were useful just 14 percent of the time despite being available for 33 percent 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 percent without useful CCTV to 55.7 percent with it – while for criminal damage the likelihood quadrupled from 10 percent to 40 percent.
Detection rates for thefts were extremely low without CCTV evidence – just 2 percent of thefts from a person were detected without the use of cameras, the study found.
"This study is the first to look at both availability and usefulness of CCTV," said Dr Matt Ashby, lead researcher and criminologist in Nottingham Trent University's School of Social Sciences.
He said: "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 reported in the European Journal of Criminal Policy and Research.
Explore further: If surveillance cameras are to be kept in line, the rules will have to keep pace with technology
Matthew P. J. Ashby. The Value of CCTV Surveillance Cameras as an Investigative Tool: An Empirical Analysis, European Journal on Criminal Policy and Research (2017). DOI: 10.1007/s10610-017-9341-6