Korgan was one of only twelve active Medusans in Starfleet as of the late 2370s. He chose an assignment on Earth as he discovered on his first training voyage in Starfleet that warp travel made him violently ill.
Korgan was the lead prosecuting attorney in the court-martial of Jean-Luc Picard. After seeing through Wesley Crusher's disguise during the court martial and his assistance of clearing Picard's name, Crusher chose Korgan as his apprentice. (ST novel: A Time to Be Born, ST novel: A Time to Die)