The investigation examined potential criminal violations of the Clean Water Act by the multistate mining operations largely run by Justice’s son, Jay, according to current and former officials familiar with the matter.

The criminal probe was a significant escalation in the yearslong effort to police serial pollution offenses by Virginia-based Southern Coal and dozens of affiliated mining operations controlled by the family. In the past decade, Southern Coal and other Justice corporations have racked up tens of thousands of alleged violations of the Clean Water Act and have been sued repeatedly by state and federal prosecutors over their failure to properly follow environmental laws at their mining sites.