The head of the U.S. audit regulator said former staff involved in stealing inspection details to share with a Big Four audit firm was an anomaly, but it plans to add two key staff positions to ensure that nothing similar happens again.

William Duhnke, Public Company Accounting Oversight Board chairman, said it plans to add risk and compliance officers as part of its response to the arrest of two former board staff members.

“I see that particular event as an anomaly,” Duhnke said in a speech to the American Law Institute’s accounting liability conference Oct. 18 in Washington.

To Ensure...