BECKLEY, W.Va. (AP) -- A former president of a Massey Energy subsidiary implicated the company's chief executive officer for the first time in safety violations as he pleaded guilty Thursday to charges resulting from an investigation into the 2010 explosion at a Massey mine that killed 29 men.

David Hughart, 54, entered the plea to two federal conspiracy charges in U.S. District Court. He was accused of working with others to ensure miners at White Buck Coal Co. and other Massey-owned operations got advance warning about surprise federal inspections between 2000 and March 2010.

The judge asked Hughart if there was a policy to give advanced warnings and, if so, what company officials ordered the policy.

"What officers are you talking about?" Judge Irene Berger asked.

"The chief executive officer," he replied.

The CEO at the time, Don Blankenship, was not mentioned by name. Assistant U.S. Attorney Steve Ruby declined comment about Blankenship after the hearing because the investigation remains ongoing.

Blankenship did not immediately respond to messages Thursday. Nor did an attorney who represents him in a civil lawsuit related to the Upper Big Branch disaster.

While Hughart did not name the CEO in court, his wife of 36 years, Karen, told reporters outside the courthouse it was Blankenship.

"I answered the phone (from Blankenship) on several occasions," Karen Hughart said. "Don called the office and at home."

Blankenship retired about eight months after the explosion at the Upper Big Branch mine and is the man who many families of those killed have said they'd like to see prosecuted. Massey has since been bought out by Virginia-based Alpha Natural Resources (NASDAQOTH:ANRZQ).

Hughart was cooperating with investigators, a sign that authorities may be gathering evidence to target other Massey officials in their ongoing investigation. Prosecutors have declined to say who else could face charges in the wide-ranging and continuing probe of the worst U.S. coal mine disaster in four decades.

Blankenship has been re-emerging as a public figure over the past year, launching a website where he shares his thoughts and reviving a long-dormant Twitter account.

His downfall began April 5, 2010, when Massey's Upper Big Branch mine exploded and killed 29 men in southern West Virginia. On a website updated recently, Blankenship calls it one of the worst days of his life.

Many people in West Virginia's coalfields hold Blankenship personally responsible for the blast, accusing him of putting profits before people throughout his long career as an operator. Multiple investigations found the explosion at Montcoal was caused by blatant disregard of federal safety laws, and Blankenship had a well-documented record of micromanaging his mines.

Hughart became the highest-ranking of three former mine workers convicted since the investigation began into the explosion at Upper Big Branch mine. He faces up to six years and a $350,000 fine when he's sentenced on June 25. Hughart and his attorney, Michael Whitt, were not immediately available for comment after the hearing.

Four investigations into the Upper Big Branch explosion have concluded that Massey concealed problems at the mine through an elaborate scheme that included sanitized safety-inspection books and an advance-warning system. The mine has since been sealed.

Prosecutors also have negotiated a $210 million agreement with the company that bought Massey, Alpha Natural Resources, to settle past violations at Upper Big Branch and other Massey mines. That protects the company from criminal prosecution but leaves individuals open to it.

Gary May, a former superintendent at the Upper Big Branch mine where the blast occurred, was sentenced last month to 21 months in prison for his guilty plea to charges he defrauded the government through his actions at the mine. That included manipulating the mine ventilation system during inspections to fool safety officials and disabling a methane monitor on a cutting machine a few months before the explosion.

May had testified at the February 2012 sentencing of former Massey security chief Hughie Elbert Stover, who was sent to prison for three years for lying to investigators and ordering a subordinate to destroy documents. It was one of the stiffest punishments ever handed down in a mine safety case. In December, a federal appeals court upheld Stover's conviction.

U.S. Attorney Booth Goodwin has said his office is sifting through a large amount of information on Upper Big Branch, and the investigation that has moved up the management ladder will continue until all avenues are exhausted. After May was sentenced, Goodwin didn't mention Blankenship when asked about him, noting instead that Hughart supervised a group of mines and had a long career at Massey.


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