Codename: SURGEON
From Halopedia, the Halo wiki
SURGEON was a code name used by a male ONI operative and leader of Operation: HYPODERMIC in 2552. "Surgeon" was contacted by Codename: COALMINER of a potential breach of security when Cortana broke into the ONI database and discovered that the Circumference was an ONI prowler. "Coalminer" then deleted the ship from the Reach database.
NOTE: "Surgeon"'s true name and rank are unknown. It is plausable that he is Colonel James Ackerson but this is in no way confirmable.
