Many knew him, though not personally.They could only catch glimpses of him as he flitted through buildings, undeterred by time constraints.He often let them see him, in a futile attempt to disrupt their schedule.This time, though, he had a plan.He cracked a grin, showing many absent teeth as he thought about it.Today was the day, he had had enough waiting.His white mask flashed through the night as he neared ground zero, jumping from rooftop to rooftop with catlike ease.He dove and rolled under a heating conduit as a police chopper buzzed loudly overhead,searchlight seeking any thing that resembled loitering.Tensly waiting,the man finally heard the chopper leave, and resumed his run across the rooftops.He found his target finally, a large and ordinary looking storage unit on top of a building overlooking the main transit route.He looked below,watching people scurry around, not wanting to be late for whatever job they had.He laughed and pressed a button,releasing his payload on the unsuspecting citizens below.