Let me take a shot at this maple. Going from past experience with similar situations and just some guessing.
You are talking about a high profile job. The business or in this case, UNL tells the search firm what they are looking for in candidates, salary, expectations, job description etc. They may ask for some names that they may have in mind or not. Then the search committee outs the package together to present to candidates. They handle contacts, phone calls, ads, scheduling etc. I don't think you realize the amount of work involved in this high level process. It could literally be a full time job for one person at UNL. Who would do it at UNL? That is what search companies are good at. You also take the biased out if it. The search company doesn't care, they are going off if criteria already established.
Generally the search committee will bring names to the UNL committee with recommendations from follow up info. The UNL committee then conducts interviews and the search committee manages all if the communication. I have headed up two of these, obviously WAY smaller than this and have been contacted by a search committee as well. There are variances on how they do things but this is a guess. The search committee may even send multiple people to the place where candidates work and find out all they can about the person.
I am glad they are using a search committee. It is a big job and you want it done professionally.