Robertson subsequently edited Gordon Parks' 1971 film Shaft, which was his last credit as a film editor. By this time Robertson had turned to directing. In addition to television programs and documentaries, he directed the feature Melinda (1972). He spent most of his remaining life in Trinidad and Tobago. There he produced and directed the film Bim (1975), and ran a filmmaking school. He returned to the United States in 1986.