Nooses have been looped over a tree at the University of Maryland , knotted to the end of stage-rigging ropes at a suburban Memphis theater , slung on the doorknob of a black professor 's office at Columbia University in New York , hung in a locker room at a Long Island police station , stuffed in the duffel bag of a black Coast Guard cadet aboard a historic ship , and draped around the necks of black dolls in the Pittsburgh suburbs .