Depends on company size. I am in a <100 employee company that is not a software organization. I lead the IT group (12 including myself). I report to the COO. He participates in interviews for candidates who would be in my group -- even those that report to one of my supervisors.
Even in larger groups, I wouldn't be surprised if the CTO participated deeper than you might at first assume.
Even in larger groups, I wouldn't be surprised if the CTO participated deeper than you might at first assume.