For instance, while both MSHA and the Illinois Department of Natural Resources said at various times during the past month that CO levels occasionally had been elevated, neither agency would release actual numbers. MSHA also said, meanwhile, that elevated levels of hydrogen were detected in the mine during the weekend of April 23-24, but had subsequently decreased.

A spokesman for DNR, which largely had deferred to MSHA in the matter, said on April 30 the state agency was “still waiting for a plan to be approved by MSHA before anyone can go underground at the mine” to conduct an on-site inspection.

Nearly two weeks earlier, on April 17, the same spokesman said company, state and federal officials were finalizing a plan “to conduct an underground assessment” of Deer Run, one of Foresight’s newest and largest producers in Illinois. The mine produced 5.5 million tons of coal in 2014 and had turned out about 1.3 million tons in January and February of 2015, an average of about 650,000 tons per month.

For several weeks, nitrogen was pumped into the mine through several boreholes drilled from the surface, ostensibly to lower CO concentrations. An MSHA spokeswoman said on April 28 that officials at the mine were “prepping for injection of remote seal material” and that “all drilling has been completed.”

Also unclear was whether there was, or had been, a fire burning in the mine, or perhaps a hotspot, that might have been responsible for higher CO levels. A government official said there was a fire, but that could not be corroborated by the state or the St. Louis-based company.

Indeed, Foresight said virtually nothing publicly about Deer Run’s idling until April 28, when it released a statement that described published references to elevated hydrogen levels as “misleading.” Hydrogen readings “have not been considered at dangerous levels,” the company said, “and they were lower than certain of the readings taken during the last 13 days. Current readings show that hydrogen and CO levels remain at or near ambient levels.”

The MSHA spokeswoman did not comment on the ambient level claim. A DNR official, however, said CO readings had been, at least at times since March 26, above ambient levels.

Foresight also owns the Sugar Camp Energy and Williamson Energy longwall mines and the Macoupin Energy, or Shay No. 1, continuous miner operation in Illinois. In 2014, the company produced more than 22 million tons of coal.

In mid-April, Foresight and Ohio-based Murray Energy closed on a $1.37 billion partnership deal, creating a company that should produce between 85 to 90 million tons of steam coal in 2015.