CHARLESTON, W.Va. -- U.S. Attorney Booth Goodwin promised Thursday that a sprawling criminal investigation of the Upper Big Branch Mine Disaster is far from over, and said critics of the probe's results to date should not assume the inquiry won't reach higher up the mine's management ladder.

Goodwin said federal investigators are examining a variety of ways to file more charges, including whether any two or more company officials conspired to violate federal mine safety laws -- a strategy not used previously against the coal industry.

"It hasn't been in the playbook," Goodwin said in an interview with the Gazette. "But we're not operating under the prior playbook."

Goodwin discussed the ongoing investigation a day after a federal jury in Beckley gave his office its second conviction in an 18-month probe of the worst U.S. coal-mining disaster in nearly 40 years.

A 12-person jury found Upper Big Branch security chief Hughie Elbert Stover guilty of two felonies: lying to federal agents and trying to destroy evidence. When sentenced in February, Stover will face up to 25 years in prison.

Last month, former Upper Big Branch miner Thomas Harrah was sentenced to 10 months in jail. Harrah pleaded guilty to faking a foreman's license when he performed key mine safety examinations at the mine between January 2008 and August 2009 and to then lying to investigators about his actions

Earlier this week, United Mine Workers officials issued a reported that labeled the April 2010 explosion that killed 29 workers "industrial homicide," and demanded more prosecutions of top officials from the former Massey Energy.

And Stover's defense lawyer, former U.S. Attorney Bill Wilmoth, argued to jurors that his client was little more than a scapegoat, while prosecutors had not brought charges against "the real villain or villains in this disaster."

But Goodwin said the two convictions for misleading investigators are important, especially in the coal counties of Southern West Virginia, where the industry's economic and political power can keep some witnesses from coming forward and prompt others to be less then truthful. Goodwin said prosecutors had hoped to get honest testimony from Stover, who sometimes provided personal security for former Massey CEO Don Blankenship and other corporate officials.

"What we wanted, bottom line from him, was cooperation, and he provided the exact opposite," Goodwin said. "This sends a message that you should not lie and you should not obstruct this investigation."

The Harrah case provides a glimpse at how obstruction not only hides information from federal investigators, but also sends agents off in other directions that eventually prove less than fruitful.

Initially, Harrah told agents that Massey officials had helped him obtain a fake foreman's certificate. Investigators began pursuing that lead, only to find that Harrah's had lied to them and had acted alone.

Goodwin said investigators were quick to pick up on Harrah's false statement, but acknowledged such an incident "takes resources away from the ultimate point of the investigation."

In this case, Goodwin said that ultimate point is a slow and methodical effort to find out what caused the mine explosion, and then uncover any criminal activity involved.

"We're taking small chunks," Goodwin said. "If you bite off an enormous deal like what caused the explosion, that's just mind-boggling what it would require, if it's even possible."

Goodwin said federal investigators are examining a variety of ways to file more charges, including whether any two or more company officials conspired to violate federal mine safety laws -- a strategy not used previously against the coal industry.

"It hasn't been in the playbook," Goodwin said in an interview with the Gazette. "But we're not operating under the prior playbook."

Goodwin discussed the ongoing investigation a day after a federal jury in Beckley gave his office its second conviction in an 18-month probe of the worst U.S. coal-mining disaster in nearly 40 years.

A 12-person jury found Upper Big Branch security chief Hughie Elbert Stover guilty of two felonies: lying to federal agents and trying to destroy evidence. When sentenced in February, Stover will face up to 25 years in prison.

Last month, former Upper Big Branch miner Thomas Harrah was sentenced to 10 months in jail. Harrah pleaded guilty to faking a foreman's license when he performed key mine safety examinations at the mine between January 2008 and August 2009 and to then lying to investigators about his actions

Earlier this week, United Mine Workers officials issued a reported that labeled the April 2010 explosion that killed 29 workers "industrial homicide," and demanded more prosecutions of top officials from the former Massey Energy.

And Stover's defense lawyer, former U.S. Attorney Bill Wilmoth, argued to jurors that his client was little more than a scapegoat, while prosecutors had not brought charges against "the real villain or villains in this disaster."

But Goodwin said the two convictions for misleading investigators are important, especially in the coal counties of Southern West Virginia, where the industry's economic and political power can keep some witnesses from coming forward and prompt others to be less then truthful. Goodwin said prosecutors had hoped to get honest testimony from Stover, who sometimes provided personal security for former Massey CEO Don Blankenship and other corporate officials.

"What we wanted, bottom line from him, was cooperation, and he provided the exact opposite," Goodwin said. "This sends a message that you should not lie and you should not obstruct this investigation."

The Harrah case provides a glimpse at how obstruction not only hides information from federal investigators, but also sends agents off in other directions that eventually prove less than fruitful.

Initially, Harrah told agents that Massey officials had helped him obtain a fake foreman's certificate. Investigators began pursuing that lead, only to find that Harrah's had lied to them and had acted alone.

Goodwin said investigators were quick to pick up on Harrah's false statement, but acknowledged such an incident "takes resources away from the ultimate point of the investigation."

In this case, Goodwin said that ultimate point is a slow and methodical effort to find out what caused the mine explosion, and then uncover any criminal activity involved.

"We're taking small chunks," Goodwin said. "If you bite off an enormous deal like what caused the explosion, that's just mind-boggling what it would require, if it's even possible."

Goodwin's office had three attorneys at the trial for the Stover case, and two others are also assigned to Upper Big Branch. Most of the crimes they would consider prosecuting have a five-year statute of limitations, giving them plenty of time to develop more cases.

Some of the nation's most fierce advocates for coal-mine safety are pleased with Goodwin's progress, and believe federal investigators will eventually bring more charges.

Tony Oppegard, a longtime mine safety lawyer in Kentucky, said Thursday that it's important to prosecute anyone who pretends they have the proper foreman's training and credentials to conduct mine safety examinations.

"To me, that's a particularly egregious act and it's more widespread than people think," Oppegard said.

Oppegard also said it was important to send a message that obstructing the disaster probe would not be tolerated, given the accounts of former Upper Big Branch miners about intimidation of workers with safety concerns.

"I see this as a beginning point and the prosecutors sending a message that if you lie to us, you're in trouble," Oppegard said.

So far, Alpha Natural Resources, which in June acquired Massey Energy, has declined to comment on the latest criminal conviction in the Stover case.

Ted Pile, a spokesman for Alpha, said that his company continues its own investigation of Upper Big Branch, but does not have a timeline for completing that "thorough and exhaustive" effort.

An independent investigation, a union probe and preliminary findings of the U.S. Mine Safety and Health Administration have all blamed the explosion on Massey's routine failure to maintain mining equipment, provide adequate underground ventilation and properly clean up explosive coal dust from mine tunnels.

Federal mine safety law makes it a crime to knowingly and willfully violate a safety or health standard. But doing so is only a misdemeanor, punishable by up to one year in prison. Falsifying a variety of mine safety reports required by MSHA is a felony that carries up to 5 years in jail.

Frequently in mine safety prosecutions, charges of lying on MSHA reports are brought against low-level section foremen whose jobs involve signing those reports. Those same foremen -- or lower-level subsidiary firms listed as mine operators -- are typical targets for charges of willfully violating safety standards.

That's what happened after the January 2006 fire that killed miners Don Bragg and Ellery Hatfield at Massey's Aracoma Alma No. 1 Mine in Logan County. Massey subsidiary Aracoma Coal Co. paid a $2.5 million criminal fine. Five of the subsidiary's mid- and low-level foreman later pleaded guilty to misdemeanor charges. No one went to jail.

Pat McGinley, a West Virginia University law professor who served on Davitt McAteer's independent probe of Upper Big Branch, noted this week that only one of the four combined criminal counts in the Harrah and Stover cases stemmed from mine safety laws. Prosecutors used more general laws that make it a crime to lie to federal agents or try to conceal or destroy evidence in a federal investigation, McGinley said.

"Federal prosecutors have numerous tools available should they find criminal conduct led to the UBB disaster," McGinley said. "It appears that the Justice Department attorneys are carefully examining an enormous amount of evidence to determine if there are persons who should be held criminally responsible for the deplorable conditions that led to the UBB disaster."

Reach Ken Ward Jr. at kw...@wvgazette.com or 304-348-1702.