CHARLESTON, W.Va. -- Six weeks after the Upper Big Branch Mine blew up, someone slipped some papers under Bob Hardman's door at the U.S. Mine Safety and Health Administration's district office in Mount Hope.
MSHA's Southern West Virginia district manager found two memos, detailing serious methane leaks in 2003 and 2004 at the Massey Energy mine where 29 workers had just been killed in a massive explosion.
The memos -- both six years old -- detailed how the Upper Big Branch Mine's floor was a likely source of explosive gas, and gave clear recommendations on what Massey should do to avoid a potentially deadly methane blast. Massey never implemented those recommendations, and MSHA officials admit they never made sure the company took action.
"I've not found any information to indicate that it was addressed in any way," Hardman told Upper Big Branch investigators, according to an interview transcript that MSHA has refused to formally make public.
Now, after a 20-month probe, a team of MSHA investigators has concluded that the worst U.S. coal-mining disaster in nearly 40 years was likely ignited through exactly the mechanism warned of in the memos Hardman found slipped under his door.
MSHA investigators concluded "a small amount of methane, likely liberated from the mine floor" in the same area of underground rock fractures as the earlier gas "outbursts."
At the same time, MSHA continues to refuse to explain how and why it didn't do something that might have prevented the April 2010 explosion.
Joe Main, the Obama administration's assistant labor secretary in charge of MSHA, said the issue is among those about agency performance that are being examined by an MSHA interview review team that has not yet been completed its work.
During a press conference Tuesday, Main also tried to deflect any blame from MSHA back toward Massey Energy, which owned and operated the Raleigh County mine.
"One of the things we can't miss here is the mine operator had the information that was available on how to address the problem," Main said.
But Davitt McAteer, a former MSHA chief who is conducting an independent review of Upper Big Branch, said Wednesday that federal officials clearly failed to do their jobs.
"When you have this known problem, the failure to address it is a failure of enforcement that is profound," McAteer said in an interview.
In a preliminary report issued in May, McAteer and his team of experts did not specifically identify methane from the mine floor as the likely source of the gas that ignited on April 5, 2010.
The McAteer report listed the failure to take action after the earlier incidents as a failure on the part of both Massey and MSHA. The report said mine operators have a responsibility to deal with such problems.
"The problem, of course, is that not all mine operators are prudent," the McAteer report said. "If MSHA has knowledge, data or evidence that a mine operator does not take his responsibility seriously and does not take all necessary precautions to protect miners' safety, MSHA must step in."
Government and independent investigators have all agreed that most of the deaths at Upper Big Branch occurred because what should have been a small methane ignition turned into a huge coal-dust explosion because Massey did not keep underground tunnels free of highly combustible coal dust.
But in the report made public Tuesday, MSHA officials classified the failure to take steps to control methane leakage from the Upper Big Branch mine floor as a violation that contributed to the disaster.
"The mine has a history of methane incidents on prior longwall panels," the MSHA report said. "These incidents put the operator on notice for methane hazards on the longwall face."
MSHA cited Massey with "moderate negligence," while noting that the company did not implement agency recommendations -- such as drilling de-gasification holes or increasing fresh-air flow to the mine face -- after the earlier methane incidents.