The Auditor General has the powers of a commissioner, under the Inquiries Act, which in fact means that the Auditor General can compel testimony. He doesn't have to go to a court to order it. The Auditor General can order it himself.
I don't know that it has ever actually been used, but it is a provision. I think it's section 13—I'll have to look it up tonight—that does have that power to compel testimony.