West Virginia coal baron Don Blankenship has been found guilty of conspiring to violate mine safety standards. But the former executive was acquitted on charges of securities fraud and making false statements to regulators, a federal judge announced Thursday.

As the CEO of Massey Energy, Blankenship oversaw the deadliest coal mining disaster in a generation. An explosion at Massey’s Upper Big Branch Mine in April 2010 killed 29 miners in West Virginia. The executive was not on trial for causing the tragedy, but faced charges over safety issues linked closely to the disaster.

“The defendant ran Massey in a way that violating mine laws was inevitable and he knew it,” U.S. Attorney Booth Goodwin told jurors during closing arguments, according to the Charleston Gazette-Mail. “He knew that you simply could not mine the amount of coal he demanded with the limited amount of people he was willing to devote and the resources that he was willing to devote without breaking the law. And he kept right on doing it.”

Blankenship faces up to one year in prison on the conspiracy charge to break mine safety regulations, a misdemeanor. His attorney Bill Taylor told reporters he will appeal. In addition to that charge, Blankenship was accused of misrepresenting the company’s safety record to securities regulators and to investors. Together, the three counts carried a maximum penalty of 30 years in prison.

The case is widely seen as the first time the CEO of a major corporation has faced criminal charges over workplace safety issues.