None of the Rotterdam shops which have installed special showers to spray would-be robbers with a synthetic dna code have been robbed since the sprays were introduced two years ago, the AD reports on Tuesday.

The spray becomes visible under a UV light and is very hard to remove, making it easier to track down criminals. The shops also carry warning signs saying the spray, which is fitted over the doors, is in use.
Twenty shops and two petrol stations in Rotterdam were fitted with the system at the end of 2008, and some 40 other shops and cafes have joined in since then, the AD says.
The paper does not say how many times the shops were robbed before the dna spray was put in place.