Locks, Lights and Lines of sight: A Randomised Control Trial Testing the Effectiveness of Simple Prevention Measures to Tackle Repeat Burglary.

Dr Emma Ashcroft1, Ms Noeline Verheyen1, Dr Melissa Smith1

1New Zealand Police


Burglary is a high-volume crime in New Zealand, with three-quarters of all burglary occurring at residential locations. Furthermore, many victims of burglary are repeat victims – a Ministry of Justice Crime and Victimisation survey (2014) established that 23% of burglary victims had been repeatedly victimised.

International research supports the use of target hardening measures – window and door locks – and measures improving surveillance and maintenance – external security lighting and foliage – to reduce repeat dwelling burglary. To test the effectiveness of these measures in New Zealand, a randomised control trial, “Locks, Lights and Lines of sight” (LLL), was implemented in four Police districts over a two-and-a-half-year period. LLL aimed to reduce the rate of repeat burglary to dwellings. Residential dwellings entered through force were randomly assigned to either a control group or an intervention group, with the intervention group offered LLL.

The rate of repeat burglary, characteristics of the repeat burglary and subjective experiences of those in both groups were compared. Previous interim analysis found no significant difference between the control and intervention group for repeat burglary rate, however the analysis did not consider whether entry to the dwelling in the repeat burglary was successful, or whether it was an unsuccessful attempt.

Final results from the trial suggest that the installation of LLL measures following burglary prevents successful entry in a dwelling as part of a repeat burglary, as well as invoking a number of unintended benefits.


Dr Melissa Smith is the Manager of Prevention Development in the Community Partnerships and Prevention Team. Melissa’s role involves the development, implementation and assessment of national harm reduction and prevention strategies, such as LLL.

Noeline Verheyen is the National Coordinator for Burglary Prevention responsible for the implementation of the LLL trial since mid-2018 and currently overseeing the development and implementation of further burglary prevention trials and initiatives.

Dr Emma Ashcroft is a Researcher for Burglary Prevention responsible for the evaluation of the LLL trial since late-2019 and currently overseeing the development and evaluation of further burglary prevention trials.