Banned by the Cambodian authorities, the documentary “Who Killed Chea Vichea?” investigates the 2004 assassination of labor leader Chea Vichea. As president of the Free Trade Union, Cambodia’s largest labor organization, Vichea was widely admired for his tireless fight to increase wages and improve working conditions for his members. It was a dangerous job which often brought him into conflict with powerful people and institutions, but despite numerous beatings, ...