How to get rid of neighborhood drug dealers

[Amy A.]

For the last year or two, cars have been parking in front of my building, leaving tons of cigarettes and glass pipes on the ground.  They live in the building across the street, whose landlord doesn't screen tenants.  There's no reason for them to be hanging around other than waiting for deals.  I've contacted the police about the glass pipe and requested more patrols.

I have been thinking about putting a sign on my building, "This area is under video surveillance", or something like that.  I hope they will go away if they think they are being watched.

What do you think?