Former Massey Energy Company Chairman and CEO Don Blankenship, seen in July 2010, has pleaded not guilty to conspiracy charges associated with the 2010 West Virginia mine explosion that killed 29 men. 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

itoggle caption Jewel Samad /AFP/Getty Images