The Associated Press reported that an order put into place last summer by US district judge Irene Berger to allow prosecutors to keep evidence under wraps was set to expire this week.
Southern District of West Virginia US Attorney Booth Goodwin has jurisdiction over the area where UBB is located.
He filed a motion last week indicating that the office had made “significant progress” in the criminal investigation, obtaining the cooperation of several witnesses including former UBB superintendent Gary May and ex-White Buck Coal subsidiary president David Hughart, which subsequently led to more witnesses.
Prosecutors said in previous filings that some individuals from the civil case might be targets of the criminal probe, including former Massey chief executive officer Don Blankenship, final CEO Baxter Phillips and former chief operating officer Chris Adkins.
According to the AP, Goodwin has argued in his motion that the criminal and civil cases “overlap heavily” and said in a previous motion that waiting for criminal evidence could benefit shareholders.
Goodwin said the public interest in “unimpeded progress” on the criminal side of the probe outweighed their concerns.
"Some individual civil defendants may be or may become subjects of the criminal investigation," he reportedly wrote.
“When civil discovery goes forward, the civil parties will gain information not otherwise available to them, allowing them to anticipate in detail the direction of the criminal investigation.”
As such, he has requested a new date of July 15, or when his office’s investigation is complete.
Massey was acquired by Alpha Natural Resources in June 2011.
The Virginia-based producer announced in April that it would close the UBB mine in Raleigh County permanently.
The investors initially filed the lawsuit in April 2010, less than a month after the explosion.
They named Alpha Appalachia Holdings and Massey officials, including Blankenship, claiming violations of the Securities Exchange Act of 1934.
The group, headed by the Massachusetts Pension Reserves Investment Trust, claimed Massey artificially inflated its stock prices from 2008 to 2010.
“Safety at Massey's mines was repeatedly sacrificed so that aggressive production goals could be met,” the group alleged in suit documentation in 2012.
“Massey had received numerous undisclosed citations arising from serious uncorrected safety and other regulatory violations at surface and underground coal mines it operates in West Virginia and neighboring states.”
According to federal records, the now-closed UBB mine was shut down by the US Mine Safety and Health Administration 48 times in 2009 alone but abatements of the violations allowed the operation to reopen shortly after.
From the beginning of 2009 until the day of the UBB mine explosion that killed 29 workers on April 5, 2010, MSHA issued 645 violations to Massey with $US1.2 million in penalties.
However, the investors were not made aware of them.
Goodwin’s criminal investigation of the blast has so far spawned three prosecutions.
Former security chief Hughie Elbert Stover is in prison in Kentucky, convicted of lying to investigators and ordering document destruction during the investigation.
Meanwhile, May is set to enter a plea this week on charges of conspiracy before Berger in Beckley and Hughart is set to enter a plea to two federal conspiracy charges on February 28.
Hughart is accused of working with unnamed parties at other Massey operations to get advance warning of surprise federal inspections between 2000 and March 2010.