The chief executive of the company that operated the West Virginia mine where 29 men were killed this year is expected to testify in a probe on the explosion.

Massey Energy CEO Don Blankenship is scheduled to testify Dec. 14 to the state Office of Miners' Health, Safety and Training.

The federal Mine Safety and Health Administration is leading the investigation of the blast, which is also the subject of a criminal probe. By law, MSHA can only subpoena witnesses if it convenes a public hearing — something the agency has so far declined to do.

State law lets investigators subpoena witnesses regardless of whether interviews are public or private.

Investigators have said a buildup of methane and coal dust might have contributed to the blast. Massey claims a sudden release of gas overwhelmed the mine and discounts the role of dust.