But Massey’s tweet storm since his release on Wednesday illustrates that even in the coal patch, bitter disputes and personal enmities can last a long time.

Blankenship was not charged with directly causing the disaster, but he was accused of violating a long list of safety standards including mine ventilation, roof support and dust control, measures that have been effective in preventing mine explosions.

And while a jury acquitted Blankenship of felony charges, several investigations into Upper Big Branch — including one by the Mine Safety and Health Administration and one by an independent panel set up by the governor — concluded that Massey’s pattern of safety lapses led to the accident.

Blankenship, however, blames the regulators. “Again one or the other lied. MSHA or prosecution witnesses. Which one is it?” he tweeted on May 11, referring to the Mine Safety and Health Administration, formerly headed by the former safety chief of the miners’ union Joe Main.