Sure they do. When the case is first brought to someone, they had to choose how in-depth they were going to look, etc. They decided that they were going to not just handle the issue at hand, but instead go searching through 5 years of email history. That was a discretionary choice.
You are 100% correct though that at this juncture, the buck stops with the highest on the food chain. Don't know who is the head of the department in charge of this kind of inquiry, but the ball is in the court of them, Jenkins, and other senior leadership.
Who fits your definition of "mid-level academics?" Nobody I can think of that fits that description has the authority to order the investigation that is under way.