There are several signs like the one above hanging in my local shopping street in Amsterdam. They signify that the surrounding area is protected by DNA spray.  Stores such as my supermarket the Albert Heijn have installed sprayers so that when a robbery occurs the robbers will be sprayed by synthetic DNA.

The DNA is invisible to the naked eye but lights up under UV light (leading to subsequent exposure under the backlight of  the Amsterdam club scene I expect). The DNA can not be removed but instead degrades around a week after the spraying. Robbers can easily be found and identified and by comparing the DNA evidence it can be established that you were at the robbery.

Powerful and scary stuff. Dutch company SelectaDNA makes the technology and says it costs around 1700 Euro for a store to implement the technology. You can see a video (in Dutch) below.

Around a minute in  you can see the effects of the DNA spray under UV light.