The head of the U.N. agency tasked with defending press freedom denounced Tuesday the killing of journalist Rubylita Garcia and called on authorities in the Philippines to investigate the case. "It is essential that the authorities of the Philippines do all they can to identify and bring to trial those responsible for this cowardly crime," Director-General of the U.N. Educational, Scientific and Cultural Organization (UNESCO) Irina Bokova said in a statement. "Murderers cannot be allowed to set limits to journalists' freedom of expression or on citizens' rights to information," Bokova said.