A superseding indictment filed Tuesday in U.S. District Court in Beckley, W. Va., accuses Blankenship of engaging in a conspiracy to falsify respirable dust samples and falsely representing the locations of sampling devices at Massey's Upper Big Branch coal mine before a massive explosion killed 29 miners in 2010.
The samples and the devices are supposed to measure miners' exposure to the mine dust that causes the deadly disease known as black lung. Excessive levels of dust can force a slowing or shutdown of the mining machines that dig coal and generate mine dust.
The new allegation is included in existing criminal conspiracy charges, which accuse Blankenship of willfully violating federal mine safety law and putting coal production before safety in the two years before the mine disaster.
The amended indictment also combines two counts in the original indictment into a single conspiracy charge. As Ken Ward of the Charleston Gazette explains, prosecutors seem to be responding to a Blankenship motion to dismiss the case.
Blankenship is also charged with misleading Massey investors and the Securities and Exchange Commission about the company's safety practices.
The case is a rare prosecution of a mining company executive for alleged safety lapses that preceded a deadly mine accident. It is scheduled to go to trial in Beckley, W. Va., on April 20.