NPR is reporting that the Mine Safety and Health Administration is one subject of a federal criminal investigation into the West Virginia mining disaster.

Sources familiar with the investigation say the FBI is looking into possible bribery of employees of the Mine Safety and Health Administration, the federal agency that inspects and regulates mining. The sources say FBI agents are also exploring potential criminal negligence on the part of Massey Energy, the owner of the Upper Big Branch mine.

Massey has been cited repeatedly for violations of federal safety regulations and unsubstantiated rumors have circulated for years that mine inspectors and other officials receive payoffs. The FBI declines comment and neither confirms nor denies that an investigation is ongoing.

In a statement to NPR, Massey Energy says it is not aware of the allegations, and is fully cooperating with any investigations taking place. The Mine Safety and Health Administration has yet to respond to a request for comment.

Advertisements