For four hours Tuesday night, investigators from the federal Mine Safety and Health Administration (MSHA) laid out their working theory about what happened April 5, just before a West Virginia coal mine exploded and 29 miners were killed.
They went through the explosion scenario step-by-step in an MSHA auditorium in Beckley, W.Va., filled with relatives of the victims, some weeping at times at the painful implications of the evidence.
NPR News has learned that safety systems were not working properly before that blast at the Upper Big Branch coal mine. Some mine safety experts believe these water-based safety systems might have helped prevent the blast if they all had been working together properly. Host Scott Simon speaks with NPR's Howard Berkes about new developments in the investigation of last year's coal mine explosion.
Legally required water systems at Massey Energy's Upper Big Branch coal mine in West Virginia were not functioning properly before the April 5 explosion that killed 29 mineworkers, according to multiple sources familiar with the disaster investigation.
Some mine safety experts believe that these safety systems might have helped prevent the explosion if they had been working as designed.