Williams and other Massey security guards have testified for the government against Stover, under deals that give them immunity from prosecution for anything they say.
Another FBI agent, Jim Lafferty, testified Tuesday about executing search warrants at Upper Big Branch in May 2010, searching various mine buildings for all sorts of documents about the operation. At the time, 30 to 40 law enforcement officers were at the scene, Lafferty said.
"We wanted to determine what caused the explosion and other matters prior to the explosion that may have involved criminal conduct at the mine," Lafferty said.
But, Lafferty told jurors, investigators didn't learn about a large stash of mine security records kept in the house across the road until Williams discussed the matter during grand jury testimony on Jan. 26, 2011.
At trial on Tuesday, Williams told jurors that he worked overtime on Jan. 11, 2011, to follow Stover's instructions to empty the security file boxes into trash bags, load them into an SUV and haul them across the road to the mine site, where he tossed them into a Dumpster.
Williams described for jurors how he followed Stover's instructions to "clean out" various items -- including security files -- from a makeshift storage area in the basement of a house across the road from Upper Big Branch.
"He said to throw all the old papers in the Dumpster, the trash compactor," Williams testified. "He said to take it out of the boxes and put it in trash bags."
After investigators learned of Williams' actions, Massey lawyers apparently discovered the Dumpster had not been emptied yet and retrieved the trash bags. Prosecutors showed jurors photographs of 20 banker's boxes containing the retrieved files.
During his opening argument, defense lawyer Bill Wilmoth had called Stover's instructions to Williams "a stupid mistake." Wilmoth said Stover had a practice of regularly disposing of old security files, and that the storage area needed cleaning because of damage from a sewage leak.
According to WSAZ-TV, Stover testified on Tuesday, when asked about Williams, "I wish I hadn't told him that ... It's the stupidest mistake I've ever made in my life."
Williams said he didn't recall ever being asked before to clean out files or other items from the storage area.
Reach Ken Ward Jr. at kw...@wvgazette.com or 304-348-1702.