It appears the Boston PD will be using drones during the Boston Marathon to look out for bad guys.
These will be “tethered” drones which of course allows them to be plugged in vs. using a battery, so their hover time is practically endless.
A tether helps in that hover time, but add challenge to flight, and height and indiscretion.
The tether also limits how far a suspect can be followed.
Interesting to say the least.