RALEIGH, N.C. (AP) — North Carolina’s top utilities regulator has been subpoenaed as part of the broadening criminal investigation triggered by last month’s massive coal ash spill that coated 70 miles of the Dan River with toxic sludge.

The North Carolina Utilities Commission on Wednesday released a copy of the subpoena ordering board chairman Edward S. Finley to testify before a federal grand jury later this month.