Updated

An ex-president of Massey Energy's White Buck Coal Co. will enter a plea on conspiracy charges in January.

David Hughart is set to appear Jan. 16 before U.S. District Judge Irene Berger in Beckley, W.Va.

Hughart is cooperating in a continuing investigation of the Upper Big Branch mine disaster. The April 2010 explosion at the former Massey operation killed 29 men. Massey and the mine are now owned by Virginia-based Alpha Natural Resources.

Prosecutors say Hughart worked with unnamed co-conspirators to ensure miners at White Buck and other, unidentified Massey-owned operations got advance warning about surprise federal inspections many times between 2000 and March 2010.

They say it gave workers time to conceal life-threatening violations that could have led to citations and shutdowns.

Hughart faces up to six years behind bars.