a spray of DNA keeps the bad guys away?

Some businesses in Holland have been using a new burglary system - one that sprays synthetic DNA on robbers as they walk out the door. The spray is deployed by an employee without the knowledge of the robber - it's odorless and invisible - and alerts the local police department. The synthetic DNA (which doesn't even cost that much to produce) is specific to the store from which it's deployed, and is meant to help cops link burglars to the scene of the crime.  Businesses that have used this system (usually installed by the police departments) have reported declines in crime rate, although there is no current data as of yet.

What could be causing this decline? The synthetic DNA alarm system hasn't been used yet to identify a criminal, but it has been triggered accidentally many times, which would allude to it being used as a scare tactic more than anything else. Businesses that have this system installed are required to have a sign posted outside alerting consumers. Even if it weren't required, it'd be a good move. The appearance of "DNA" on a sign outside of stores definitely deters prospective burglars. I don't see how synthetic DNA spray is any more effective than using UV ink, but fear of the unknown is daunting enough for most people. Even by glancing at readers' comments below the NYTimes article, I'm surprised at how little people actually understand about the use of DNA. Some worry about the prospect of being sprayed by "hybrid-human DNA", without realizing synthetic DNA is completely inactive and would cause no harm to the individual it's been sprayed on. On a more general level, I think criminals tend to associate "DNA" with "getting caught", which is enough to dissuade them.

In this case, the fear of the unknown appears to be effective enough to discourage robbers. It'll be interesting to see raw data pertaining to crime rates though...