Just shy of a year after the largest mine disaster in the last 40 years, two families of West Virginia miners who died in the Upper Big Branch mine disaster have filed wrongful death lawsuits against mine owner Massey Energy Company, who they say should have prevented the tragedy.

The West Virginia mine accident took place near Montcoal, WV, when a huge explosion roughly 1,000 feet underground killed twenty-mine miners. The investigation of the fatal accident is still ongoing, although many believe that flammable gases were ignited by a spark. The FBI, Massey Energy, the U.S. Mine Safety and Health Administration, and the State of West Virginia are all involved in the investigation, which has been made difficult because of dangerous conditions in the mines. Initial findings suggest that the mining equipment was not functioning properly and was not preventing dangerous sparks or minimizing dangerous coal dust.