I'd guess you are wrong, and I'd be willing to bet that if any get caught, they are white and native-born. And furthermore, I'd bet they are tweakers. (I wonder if Wikipedia has an entry for tweakers.) They are just your average, illegal-drug-using, welfare-recieving, all-American tweakers. And the people helping them are the people that keep drugs illegal and expensive, so that tweakers, who have nothing but time, have to steal stuff to keep their habits supplied. Flame away, but I'm right.
Most of the thieves were probably black, because nobody who wasn't black would have dared show his face in the South Bronx in those days. But the common element was that they were drug users who needed to support their habit.