David Craig Hughart, president of a Massey subsidiary that controlled White Buck Coal Co., is named in a federal information document — which signals a defendant is cooperating — filed Wednesday in U.S. District Court in Beckley.

Although Upper Big Branch is never directly mentioned in the document, U.S. Attorney Booth Goodwin told The Associated Press the charges come from his team’s continuing and wide-ranging investigation of the April 2010 explosion that killed 29 men at the southern West Virginia mine

Hughart is the highest-ranking official yet to be charged, and his cooperation suggests that federal officials are aiming their sights even higher in the former Massey leadership. Massey was bought after the disaster by Virginia-based Alpha Natural Resources, which announced this past spring it was sealing the mine permanently.

The court document accuses Hughart of working with “known and unknown” co-conspirators to ensure that miners underground at White Buck and other, unidentified Massey-owned operations received advance warning about surprise federal inspections “on many occasions and various dates” between 2000 and March 2010.

Those illegal warnings gave workers time to conceal violations that could have led to citations, fines and costly production shutdowns, the document says.

Four investigations have concluded that Massey systematically covered up problems at the mine through an elaborate scheme that included sanitized safety-inspection books and an advance-warning system.

The United Mine Workers of America, which accused Massey of “industrial homicide,” has demanded prosecution of at least 18 Massey managers, including Blankenship.

Hughart could be the link prosecutors need to go up the Massey food chain.

He’s been president of at least 10 Massey subsidiaries throughout his career, positions that would have required the consent of a CEO whose micromanagement is well documented. At Big Branch, for example, Blankenship demanded production reports every 30 minutes.

Investigators say that at other Massey mines, Hughart colluded with others to violate laws requiring adequate ventilation, the removal of explosive coal dust and the application of pulverized limestone to prevent explosions.

Hughart has agreed to plead guilty to two charges: felony conspiracy to defraud the federal government by impeding the actions of MSHA, and misdemeanor conspiracy to violate mandatory health and safety standards. The felony charge carries a possible sentence of five years in prison, Goodwin said. The misdemeanor carries up to one year.

Goodwin said his investigation is continuing, “and it’s clear from the information that there are co-conspirators, both known and unknown to us.”

He wouldn’t say who else might be charged or when. His investigators are “trying to push forward as quickly as we can,” Goodwin said, but he said that developing the necessary evidence means obtaining the cooperation of people like Hughart.

Hughart is the third person to face serious criminal charges in the mine-blast investigation.

Former Upper Big Branch superintendent Gary May is also cooperating with prosecutors. He pleaded guilty to a federal conspiracy charge for his actions at the mine and is set to be sentenced in January.

Former Massey security chief Hughie Elbert Stover, meanwhile, is appealing his conviction last fall on charges he lied to investigators and ordered a subordinate to destroy documents. He was sentenced to three years behind bars — one of the stiffest punishments ever handed down in a mine safety case — but has been free pending appeal.  Witnesses testified that Stover instructed mine guards to send radio alerts whenever inspectors entered the property. He’s denied any wrongdoing.

The explosion at Upper Big Branch was sparked by worn teeth on a cutting machine, and fueled by methane and coal dust. It was allowed to propagate by clogged and broken water sprayers. The force of the blast traveled miles of underground corridors, rounding corners and doubling back on itself to kill men instantly.

Goodwin’s office negotiated a $210 million agreement with Alpha to settle past violations at UBB and other Massey mines, protecting the company from criminal prosecution.

But individuals such as Hughart — and perhaps Blankenship — remain on the hook.

A memo suggesting Blankenship regularly ordered underlings to put profits before safety emerged during a wrongful-death lawsuit filed by the widows of two men killed in a 2006 fire at Massey’s Aracoma Coal Alma No. 1 mine.

The memo told workers that if their bosses asked them to build roof supports or perform similar safety-related tasks, “ignore them and run coal.”

“This memo is necessary only because we seem not to understand that the coal pays the bills,” it said.

Massey settled that lawsuit for undisclosed terms, and Aracoma paid $4.2 million in civil and criminal penalties.

Public records suggest Hughart worked closely for at least 15 years with Blankenship, who retired about eight months after the disaster.

Blankenship dropped out of public view for a while but has been resurfacing. Last month, he donated $300,000 to the Marshall University medical school, and he’s been posting his thoughts on politics and other matters on a website where he labels himself an “American competitionist.”

In 1998, Hughart founded Big Sandy Venture Capital Corp., listing himself and Blankenship as co-directors, according to records on file with the Secretary of State’s Office. In 2009, that company was absorbed by Massey’s Green Valley Coal Co., with Hughart serving as president.

Hughart has also been president of Massey’s Mammoth Coal, Peerless Eagle, Jacks Branch Coal, Kanawha Energy, Majestic Mining, Alex Energy, Nicco Corp and Elk Run Coal subsidiaries.

The United Mine Workers of America sued him in 1981 for alleged civil rights violations that involved repeatedly threatening, harassing and assaulting workers at the construction of a coal-preparation plant.

Federal court records show the case was settled in 1986 before going to trial.