Mine helmets and painted crosses sat 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

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

Mine helmets and painted crosses sit at the entrance to Massey Energy's Upper Big Branch coal mine, a memorial to the 29 miners killed in an explosion April 5, 2010. Jeff Gentner/AP hide caption

itoggle caption Jeff Gentner/AP

Mine helmets and painted crosses sit at the entrance to Massey Energy's Upper Big Branch coal mine April 5 in Montcoal, W.Va. The memorial represents the 29 coal miners who were killed in an explosion at the mine a year ago. Jeff Gentner/AP hide caption

itoggle caption Jeff Gentner/AP

Community members, friends and family participate in a vigil held for the victims of the Upper Big Branch mine in front of the Whitesville Elementary School on April 7, 2010. Kayana Szymczak/Getty Images hide caption

itoggle caption Kayana Szymczak/Getty Images

Emergency vehicles leave the entrance to Massey Energy's Upper Big Branch coal mine in Montcoal, W.Va., on April 5, 2010, after a deadly explosion. Jeff Gentner/AP hide caption

itoggle caption Jeff Gentner/AP