Don Blankenship, former CEO of Massey Energy, is accused of thwarting mine safety enforcement and conspiring to violate mine safety law. Massey Energy owned the Upper Big Branch mine in West Virginia, which exploded in 2010, killing 29. Jacquelyn Martin/AP hide caption

itoggle caption Jacquelyn Martin/AP

Mine helmets and painted crosses at the entrance to Massey Energy's Upper Big Branch coal mine, as a memorial to the 29 miners killed there. Jeff Gentner/AP hide caption

itoggle caption Jeff Gentner/AP

At an April 25, 2010, service in Beckley, W. Va., for the 29 miners killed in the Upper Big Branch explosion, helmets — placed on crosses — were lined up in their honor. Jewel Samad /AFP/Getty Images hide caption

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West Virginia State Police direct traffic at the entrance to Massey Energy's Upper Big Branch coal mine in Montcoal, W.Va., April 5, 2010. AP hide caption

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Mine helmets and painted crosses sit at the entrance to Massey Energy's Upper Big Branch coal mine on April 5, as a memorial to the 29 miners killed there one year earlier. Jeff Gentner/AP hide caption

itoggle caption Jeff Gentner/AP

Two officers with the Raleigh County Sheriff's Office stand guard in front of the Upper Big Branch coal mine several days after the April 5, 2010, explosion that killed 29 workers in Montcoal, W.Va. Mark Wilson/Getty Images hide caption

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Massey Energy shut down its Freedom Mine in Kentucky, which was targeted by federal regulators for the toughest enforcement action ever. Howard Berkes/NPR hide caption

itoggle caption Howard Berkes/NPR