Congressional leaders have promised hearings, and the state Office of Miners Health, Safety and Training will do a separate investigation that will coordinate with McAteer's team.
Across West Virginia on Friday, mine operators were observing a day with no underground coal production. Manchin requested the move to honor the fallen miners and to refocus workers and management on safety issues.
Also Friday, Massey published full-page newspaper ads that said the company "will do whatever is needed to attend to the needs of those who have lost loved ones in this horrific incident. This is our solemn duty, and we will meet it with a clear sense of responsibility."
The ads, headlined "An open letter to the citizens of West Virginia," also said, "Massey's members know the facts: that our mines exceed legal safety standards, that we fix safety hazards as soon as we find them, that we use the best technologies available to prevent accidents ... and that we have received national recognition and awards for safety precautions."
A day earlier, the family of miner William I. Griffith filed the first wrongful death case against Massey and its Performance Coal subsidiary stemming from the disaster. The suit was filed Thursday in Raleigh Circuit Court, and more suits are expected to follow.
Griffith and his wife, Melanie, were to celebrate their 33rd wedding anniversary on April 30. Griffith, 54, had worked for Performance Coal since 1992 and went into the mines in 1974, shortly after he graduated from high school.
Rachel Moreland, one of Griffith's lawyers, said Friday that he had been worried about safety conditions in the mine.
"He told his wife that if anything ever happened to him to get a lawyer," Moreland said.
Department of Environmental Protection officials said this week that they had not yet been contacted by the MSHA or the state mine safety office of McAteer concerning questions about surface mine blasting near the Upper Big Branch Mine.
DEP spokeswoman Kathy Cosco said that there are at least four surface coal mines in the vicinity of Upper Big Branch, with most of them being located to the south of the active mining area underground. All are Massey operations.
"The company is gathering the blast logs for the day of the explosion and is getting them to us," Cosco said. "Once we have them, we can determine the exact times and locations of shots that took place that day."
McAteer said, "We should be addressing the issues coming from the environmental side, and from the safety side."It's prudent for us to take a good look at what the impact is."