This is due to his cooperation with the blast’s continuing criminal investigation.

A spokesman for US attorneys Booth Goodwin and Steven Ruby provided ILN Wednesday with the documentation of approval by US District Judge Irene Berger for the continuance of the case against Gary May. It was filed by Ruby this week in US District Court for the Southern District of West Virginia.

“[The] defendant is cooperating in an ongoing investigation and the parties need additional time to fully develop the extent of his cooperation before sentencing and the preparation of pre-sentencing materials,” the June 8 motion, also provided to ILN, outlined.

The 60-day continuance means May will be sentenced October 4 at 1.30pm local time.

The US Attorney’s office began an investigation into whether federal officials may have provided warning to Massey Energy of upcoming inspections in April. That followed a March 29 testimony by the 43-year-old May where he pleaded guilty for impeding federal enforcement efforts during his tenure at UBB.

According to media reports, Berger asked May at the hearing who else played a role in the conspiracy to hide safety violations by working with others to provide advance notice that an inspector was onsite at the mine.

“It started, you know, from the MSHA inspectors coming on the property,” May reportedly testified under oath at the time, according to the Associated Press.

“Sometimes they would tell us, you know, they'd be back tomorrow or where they were going.

“And it went from there to telling everybody that was outside, you know, just scatter word by mouth on the phone and they would tell whoever was underground.”

He also told Berger in March that the practice by federal inspectors occurred for his entire tenure at UBB, as well as every mine he had ever been to.

Federal regulations under the Mine Safety and Health Act prohibit the advance notice of inspections by anyone, be it mine employees to others or on the part of its own federal inspectors.

The violation carries a fine of $US1000 as well as a six-month jail sentence.

Another former UBB staffer, security chief Hughie Elbert Stover, filed an appeal in April to his conviction and three-year sentence handed down earlier this year for lying to federal investigators and ordering the destruction of documents related to the events at the mine.

Owner Alpha Natural Resources acquired the UBB mine along with its takeover of Massey Energy last June. The producer announced April 4 that it would permanently close the mine.