Community members participate in a prayer service for the miners and their families, April 7, 2010. (Photo by Kayana Szymczak/Getty Images)

Yesterday,investigators shared their theorieson last April's Big Branch Mine explosion with the people who have been most affected--the victims' families. According to investigators, there probably was not a single cause. They believe that a series of controllable errors and uncontrollable circumstances led to the explosion.

The experts were careful in their phrasing around Massey Energy's culpability. They said that the  mine was "noncompliant" in multiple areas, but beyond that, deferred to criminal investigations that are currently underway.
While they presented expert testimony, the Mine Safety and Health Administration also stressed that yesterday's finding are preliminary. The agency's final report is due in 60 to 90 days.

NPR has posted excellent illustrations of the Federal agencies theories.