"Matty F" wrote

I seem to have started to attract some door bell ringing from the local
youths on the skulk home from school. I ignore it - but it has escalated
into them coming up to the windows and knocking on them (to really
impress
their mates)

A cheap solution is a dummy video camera (with a flashing red light on
it) above the door so it can be seen easily.
A continuously recording video camera is great if you know the time an
incident happened but otherwise it's a pain to search through hours of
recording. Best would be a camera that records on your computer when
it detects movement.
A local shopkeeper borrowed a video camera which got a good picture of
a tagger's face, which he then put in the window of his shop. Helpful
locals told him the name and address of the tagger, and that was
written on the picture. There's been no tagging since.

Tagging?
Method to improve organisation of images in database?