Criminals in Croydon will be receiving a Valentine's Card from an unwelcome admirer this week - the police.

The card, to be sent out to all known burglars and robbers, reads: "Thinking of you and what you do at this time of year".

Another card refers to the police's new "Smartwater" crime detection technique that helps trap crooks. It reads: "Rose are Red, Violets are Blue, When Smartwater is activated, it's over for you."

Smartwater, a UV sensitive fluid, is the latest method to help reduce burglaries and robberies in the borough. Painted onto household items the solution leaves a forensic fingerprint encoded with the owner's details, which is virtually impossible to remove, linking suspects to the scene of a crime.

A liquid spray is also available, acting as a deterrent. When activated by thieves the substance lets off a fine spray which sticks to hair, skin and clothes for months, even after washing.

Smartwater kits have been handed out to over 2,000 homes in burglary blackspots, with ten schools also having installed Smartwater to protect thieves from valuable IT equipment.

Superintendent Nick Jupp said: "Croydon police remain determined to continue to reduce crime. Smartwater has played an important part in our recent crime reduction."