Massey spokesperson Jeff Gillenwater acknowledged the FBI had conducted interviews, but said the company is "not aware of the nature of their investigation. We intend to cooperate in all phases of the accident investigation."
At the core of the probe are questions of whether the company engaged in criminal negligence.
The FBI's move adds yet another front to Massey's battle to save face in the wake of the disaster. Already under fire for a history of safety violations and CEO Don Blankenship's systematic downplaying of safety concerns, the company last week hired a Texas PR firm run by a former Bush White House communications expert to fight bad publicity.