The party or parties who investigate a campus sexual assault case will vary by school. Different schools use different processes. Say A is not necessarily reflective upon the size of the school, but a larger school, for example, may have more dedicated parties, say specifically that fill this role. Title IX investigators that is. Smaller schools sometimes have overlap. It could be, for example, the coach who's actually doing the investigation. I've seen that situation before where there's potential conflict.
Some schools outsource to private law firms to conduct a Title IX investigation. Some schools use a combination approach where there's a person at the school who is an assigned investigator, and then there's an attorney on the outside who's also, say, do investigator, working together. It can vary tremendously because of the nuances and considerations in the Title IX investigation. It's critical to have an experienced attorney advisor helping through the process. They can try to ensure the most favorable outcome through the investigative process.