WASHINGTON — The Supreme Court is leaving in place the conviction of ex-Massey Energy CEO Don Blankenship for misdemeanor conspiracy to violate federal safety standards at a West Virginia mine where 29 miners died in 2010.

The court declined Tuesday to take up Mr. Blankenship’s case. Mr. Blankenship, who recently finished a one-year prison term, had asked the court to review his conviction, which a federal appeals court upheld in January.

Mr. Blankenship had said he’s “more than 100 percent innocent” and the case was colored by emotion and publicity. He says natural gas caused the explosion at the Upper Big Branch Mine, and the trial judge erred in instructing the jury and limiting cross-examination.

Four investigations found worn and broken cutting equipment created a spark that ignited accumulations of coal dust and methane gas.

United Mine Workers of America International President Cecil E. Roberts applauded the decision.

“It’s instructive to look at the record. First, Don’s whack-job theory of what happened at the UBB mine has been deemed false by two state investigations, one federal investigation and one done by the UMWA,” said Mr. Roberts. “Second, he has been convicted in federal court of setting up a scheme to circumvent federal mine safety and health law. His appeals have been denied at every judicial level, including now by the Supreme Court. He served an all-too-short sentence in a federal penitentiary for his crime. He is a convict, and he will always be one.

“It’s time for him to go back to Las Vegas,” said Mr. Roberts, “and allow the families of those killed under his watch at Massey to live their lives free from his miserable attempts to blame others for his own misdeeds.”

First Published: October 10, 2017, 7:41 p.m.