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

A memorial at the entrance to Massey Energy's Upper Big Branch coal mine represents the 29 coal miners who were killed in an explosion in 2010. Jeff Gentner/AP hide caption

itoggle caption Jeff Gentner/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

Coal miner Lee Hipshire in 1976, shortly after emerging from a mine in Logan County, W.Va., at the end of his shift. A few years later, Lee took early retirement because of pneumoconiosis, or black lung disease. He died at 57. Courtesy of Earl Dotter hide caption

itoggle caption Courtesy of Earl Dotter

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

itoggle caption Jewel Samad /AFP/Getty Images