In Arkham City, you can interrogate enemies to get hints (markers on the map) of where to find Riddler's trophies. I've finished the game now, and finished all sidequests, but I still have 6 trophies to find (spread between Park Row and Amusement Mile). Problem is: I've soaring Arkham for a couple of days now and haven't found anyone to interrogate anymore.
Therefore I ask, is it normal that there are no hints for the last few trophies? (Am I meant to find them on my own?)
Or should I keep looking for people to interrogate?