Federal prosecutors are looking into whether the Mine Safety and Health Administration (MSHA) might have tipped off Massey Energy Company officials about inspections, prior to the events that led to the 2010 explosion at the Upper Big Branch mine. The explosion, the largest in West Virginia history, killed 29 workers.

The U.S. Attorney's office plans to look at testimony given by a former Upper Big Branch superintendent Gary May, alleging that federal MSHA inspectors regularly told company officials when they planned to visit the Massey-owned mine. May made these allegations as part of a deal to cooperate with the federal criminal investigation of the 2010 explosion. May had pleaded guilty to conspiring to violate mine safety standards and to cover up the resulting conditions.

May claimed that MSHA inspectors on the property would inform Upper Big Branch employees that they would be back to inspect the next day, and where they planned to inspect. While the inspectors only told a few individuals that they met, word would quickly spread to the other employees, including those who worked underground. May claimed that the practice predated his employment, and was a common practice at all of the mines where he had ever worked.

May's claims come in light of the fact that MSHA officials are focusing on a program set up by Massey where security guards gave underground crews notice of mine safety inspections. MSHA officials believe that these warnings gave Massey employees time to cover up any unsafe conditions at the Upper Big Branch mine and were a major contributor to the explosion.

MSHA officials disputed May's claims, stating that the agency never tipped off any workplace of a mine safety inspection. Information regarding inspections is meant to be restricted solely to MSHA personnel. Anyone who provides an advanced warning of an MSHA inspection faces up to six months in prison and $1,000 in fines.