The Dynamics of Crime Investigation

Considerable efforts have been made to explore ways to prevent crime by studying how and where it arises. Much less is known about what happens after a crime has been reported. Here, we analysed a cohort of crimes from an outcome database released monthly by the UK Home Office. The data documents the disposition of a crime report through a range of outcomes beginning with “under investigation” and converting to other outcomes (e.g. “unable to prosecute”) over a 39-month period. We found that the reduction in the number of “under investigation” reports and the appearance of new designations follow either a one- or two-component exponential decay process. The rates of decay vary by police force, crime type, and new outcome designation. Crimes like bicycle theft (0.472 month ^-1 ) and vehicle crime (0.478 month ^-1 ) tend to be resolved quickly while investigation of violence and sexual offences proceed more slowly (0.207 month ^-1 ). The crime type consisting of violence and sexual offences shows low variability across the 42 forces investigated indicating a more standardized approach to these crimes. When looking at the rate processes, the different rates are not competing to act on all crimes together. Rather, there are different pools of crimes and outcomes which are acted upon separately. Metrics obtained from the dynamic process of investigating crimes provide unprecedented insight into policing once a crime report is made.