Colonel, former leader of Colonel Harold Maybourne's rogue N.I.D. operation to illegally procure technologies to defend Earth against the Goa'uld. Grieves was captured by Jack O'Neill, traveling back to Earth to prevent imprisonment with the Asgard. He was quickly arrested and charged with high treason against the United States and its allies.
Grieves was visited by O'Neill, offering to be taken off death row if he offered his services to solving a problem he created with the Sentinel, a powerful enemy eradication device on the planet Latona. He and Lieutenant Kershaw had dismantled the weapon while under Maybourne's service. Grieves eventually agreed and traveled with SG-1 back to Latona where he and Kershaw worked to fix the device.
Grieves momentarily laid down cover fire with a hand gun, proving he could temporarily be trusted with a sidearm. With encouragement from Kershaw, Grieves explained that he shot and killed the caretaker of the Sentinel, preventing the device from performing its task. Grieves laid down his life for the device, providing the final organic piece to its operation that initiated the burst of energy, eliminating Goa'uld ground and orbital forces from Latona.
The Sentinel - Grieves travels back to Latona to fix a problem he swears he never created while working in the Rogue N.I.D. arm.