It has been very costly in the past , 30k + for just the lidar, another 10k+ for the heavy lift drone capable of carrying it. This is why LE doesn't utilize this method to search. Just recently a company released a $100 lidar that can fit on smaller drones. Velodyne Lidar Introduces Velabit™ | Velodyne Lidar With the Velabit lidar, it places this method in reach of regular search teams. Dia may not be on the property means that there is a possibility that she could be. Eliminating the possibilities will leave the probabilities of other locations.