Families of killed miners speak out

It was the worst U.S. mining disaster in 40 years. In 2010, a massive explosion tore through the Upper Big Branch mine in Montcoal, West Virginia, killing 29 miners. On 60 Minutes this week, Anderson Cooper explores the dangerous safety violations prosecutors say the mine's owner, Massey Energy, and the company's CEO, Don Blankenship, willfully ignored.

Patty Quarles, whose son Gary Wayne died in the mine, and several other family members of miners killed in the explosion, were a constant presence in the courtroom during Blankenship's trial last fall.

"He was my son," Patty Quarles tells Cooper in the previously unaired clip above. "This is the last thing that I can do to try to help him get any kind of justice."

Investigators believe the blast was caused by a spark that ignited methane gas that had accumulated due to inadequate ventilation. Blankenship, whose company owned more than 40 mines in central Appalachia, was found guilty of conspiring to violate mine safety laws.

"We've been fighting now for five and a half years," Quarles says. "He needs to go to jail."

Shawn Ellison, a miner at Upper Big Branch, would have been working the day of the explosion -- but he happened to call in sick. "The last nine guys they brought out, that was my whole crew," he tells Cooper. "Right there where the explosion happened at was where I'd have been."

Ellison says he thought of his co-workers as a "second family," working long shifts with them at the mine. "It was hard," he says, eyes teary. "It's still hard to this day."

Bobbie Pauley was the only female miner at Upper Big Branch. She wasn't working on the day of the explosion, but her fiancé Boone Payne was killed in the blast. She tells Cooper she and other miners knew their work was unsafe.

"Everybody says, 'Well you know, why didn't you speak up?'" she explains. "We did speak up. I spoke up. I spoke up to my supervisors about methane that I was concerned about. I got yelled at, you know, for saying something."

She tells Cooper that when it comes to employment in West Virginia, mining is "the only game in town." And she and her colleagues, including some third-generation miners, were committed to the state where they were raised. "It's such a loving, loving state, you know? And coal miners are the biggest part of that state," she says. "I mean, they're the heartbeat of West Virginia."

Editor's Note: Since these videos were originally published in March 2016, Don Blankenship began serving a one-year sentence at a federal prison in California.