The OPR investigator Jimmy genuinely wasn't familiar with, the one he knew best was Agent Fuller, who had always initiated the investigations against him before, but this time it wasn't Fuller who came to him.
Jimmy and Ruiz had already discussed the details of the report, so he simply answered a few questions based on his submitted report, and the OPR agents left. It was clear they didn't want to open a breakthrough with Jimmy.
Also, OPR had already messed up several times with Jimmy's case. Even if they hadn't been responsible for investigating Jimmy's cases before, they knew he was a tough nut to crack, and with so many people to investigate, he wasn't indispensable.
At the end of the inquiry, Jimmy even asked the OPR agents where Agent Fuller had gone, and the result was something that truly surprised him: Fuller had been dismissed and was no longer an FBI agent.
