When Order 66 was initiated, Korizan was captured while only twelve years old and brought to Fortress Inquisitorius where he was inducted as an Inquisitor after numerous torture sessions. When his training was complete, Korizan's first and last mission was to protect Crescent Station, an ancient Sith battlestation and observatory that Darth Sidious reserved for his future plans.
In 12 BBY, the Jedi survivor Srael Mar-Qan ventured to Crescent Station and infiltrated it. He eventually made his way to the station's command center where he was confronted by Korizan. Korizan was fatally wounded in the duel that followed, though felt that his enemy had been honorable and thus deserved to access the artifact vault. He accessed the vault using the dark side of the Force in his last seconds of life, though failed to realize that the station was designed with a self-destruct procedure that'd be activated by any who opened the vault before directly connecting their dark power to the station itself - a ritual performed by only Sidious and the unknown Sith who originally commanded the station. Srael escaped the destruction with the vault's Jedi holocrons and lightsabers, and also brought Korizan's lightsaber with him.
Srael brought all of the lightsabers to Tython to be buried, including Korizan's. He restored the lightness in Korizan's crystal, returning the crystal that a young Korizan found on Ilum to its original blue color.