A radio signal sent from a half-mile away deceived the GPS receiver of a UAV into thinking that it was rising straight up. In this way, the UAV’s dependence on civil GPS allowed the spoofer operator to force the UAV vertically downward in dramatic fashion as part of multiple capture demonstrations.

Cite and download the paper:
D.P. Shepard, J.A. Bhatti, and T.E. Humphreys, "Drone Hack: Spoofing Attack Demonstration on a Civilian Unmanned Aerial Vehicle," GPS World, August, 2012.