Retailer Michael Hill Jeweller is trialling DNA sprays in its stores to combat burglaraies. The jewellery stores have been targeted by ram raids and smash n grabs several times in the past year most recently in Auckland's Albany on Friday night. DNA spray is just one of the remedies available along with the use of fog cannons. Co-director of Selecta DNA Graham Zuill explains how DNA sprays and Fog Cannons work.