As long as you haven't killed the Hunters hidden behind the well-known riddles and "quests" they will appear at several constant locations. You may have to look around a bit to find them as the range of their disrupt is rather big. For example we recently were clearing the MLK control point (on player's map who didn't yet kill all the Hunters in DC) and after killing all enemies we didn't exit combat and got that very same static. After a short while we found the Hunter stalking us from a rooftop around the corner, a block away (10th St. Northwest / F St. Northwest).
But in case you wanna take a short look at them, do not ADS while searching the rooftops – this will make them disappear directly.