Heck, they were using aerial recon (hot air balloons) to identify firepower in the Civil War, so how far have we really progressed? I think we should develop ammunition that has a shooter signature on it.
By the way, my theory on the sniper is that he is a reincarnated member of Mosby's guerillas. They used to make quite a sport of sniping and running before the 8th IL CAV put them out of business.