The children of three slain Colombian union leaders filed a lawsuit Friday reviving claims that the men's…employer was responsible for their killings outside a coal mine eight years ago. A similar lawsuit…ended with a verdict for mine operator Drummond Co. Inc. in 2007. But the plaintiffs…now have access to a key witness who couldn't testify in the first trial because he was in prison…The lawsuit was filed in federal court in Birmingham by eight children of Valmore Locarno, Victor Orcasita and Gustavo Soler, who all worked at Drummond's huge coal mine at La Loma…The lawsuit contends Drummond paid paramilitary forces to kill the men, a claim denied by Drummond and rejected by jurors…two years ago.