what types of uav are used by law enforcement for surveillance?

Answer 1

A number of civil uses with UAV's are being considered, some of which would be fire detection and prevention, traffic analyses and monitoring, surveying for sharks and other potentially dangerous marine wildlife near the coast, and agricultural enhancement.

The only location I'm aware of that are experimenting with the use of UAV's in law enforcement is in Australia.

Hope this helps.....best wishes.