This photograph from May 8 apparently shows a man in a construction helmet hurling a stone into the air from the center of the Pace University plaza.

Some observers, including the New York police, stated that students were throwing rocks onto the plaza from the balcony of the Pace building.

Others claimed construction workers initiated the rock throwing as they moved from City Hall Park onto the Pace campus.

Who started throwing rocks? Does your answer to this question change your interpretation of what happened on May 8?