CHARLESTON, W.Va. (AP) — A judge sentenced former coal executive Don Blankenship to a year in prison Wednesday for his role in the deadliest U.S. mine explosion in four decades, saying he was part of a "dangerous conspiracy."

One day after the sixth anniversary of the Upper Big Branch Mine explosion, which killed 29 men, U.S. District Judge Irene Berger gave the ex-Massey Energy CEO the maximum prison time and fined him the maximum $250,000. A federal jury convicted Blankenship on Dec. 3 of a misdemeanor conspiracy to violate mine safety standards at Upper Big Branch.

Blankenship spoke briefly during the sentencing hearing and said he wanted to reassure the families of the fallen miners that they were "great guys, great coal miners."

"It is important to everyone that you know that I'm not guilty of a crime," Blankenship said.

Blankenship's attorneys contended he should receive probation and a fine, at most. The judge denied their motion for Blankenship to remain free as he appeals. It's not clear when he must report to prison.

Outside the courthouse, a few family members of miners who were killed started yelling at Blankenship.

"We buried our kid because of you. I got to go to the grave to see my kid's casket," Robert Atkins said.

Blankenship and his attorneys were ushered into an awaiting van by about a half dozen law enforcement officers.

The sentencing capped a wide-spanning investigation into Massey following the explosion. Four others up the Massey corporate chain were convicted before Blankenship.

The judge talked about Blankenship's resume and said: "Instead of being to be able to tout you as a success story, we are here as a result of your part in a dangerous conspiracy."

During the trial, prosecutors called Blankenship a bullish micromanager who knew about and meddled in the smallest details of Upper Big Branch. They said Massey's safety programs were just a facade — never backed by more money to hire additional miners or take more time on safety tasks.

Blankenship was acquitted of felonies that could have stretched his sentence to 30 years.

The judge already ruled that Blankenship won't have to pay $28 million in restitution to Alpha Natural Resources, helping him avoid a serious blow to his personal fortune. Alpha bought Massey in 2011 after the explosion, and wanted Blankenship to pay legal fees it covered for former Massey employees, costs to cooperate with the investigation and mine safety fines incurred at Upper Big Branch.

Berger also ruled that Blankenship would not have to pay restitution to about 100 people, including former miners and family members.

At Upper Big Branch, four investigations that found worn and broken cutting equipment created a spark that ignited accumulations of coal dust and methane gas. Broken and clogged water sprayers then allowed what should have been a minor flare-up to become an inferno.

Blankenship disputes those reports. He believes natural gas in the mine, and not methane gas and excess coal dust, was at the root of the explosion.