A former contractor for the U.S.-based coal company Drummond Co. has been convicted of murder and sentenced to nearly 38 years in prison as the mastermind of the 2001 killing of two union leaders. The trial judge also ordered prosecutors to investigate Drummond's U.S.-based president and three current and former employees to determine whether they might also be responsible. The killings are the subject of a U.S. lawsuit and have drawn considerable attention because several witnesses, including the convicted man, Jaime Blanco, allege senior managers of Alabama-based Drummond ordered them. Drummond officials have denied any involvement in the killings…