No clue either...but here’s an article from back then:
http://www.businessweek.com/stories/1992-10-04/fear-eats-the-soul-in-little-tehran
Bob, I read the article. It glossed over the increases in crime and the illegal activities like selling doctored phone cards. As I said, when their density increased anger and physical attacks did, too. Japan saved itself some long term grief by getting rid of them.