A US Marine was yesterday acquitted of assaulting a police officer. Lance-Corporal Sean Crane, 20, pleaded not guilty in Western Court to assaulting Constable Wong Man-chung in an alley off D'Aguilar Street, Central, on August 13. Defence counsel Maurice Tracy said the prosecution had not proved that Corporal Crane was the person who had pushed Constable Wong down a flight of steps. Magistrate Hugh Sinclair heard that a group of officers including Constable Wong received a radio call that a possible drug offence was taking place. As police arrived, three suspects fled, one of them causing Constable Wong to fall down the stairs.