In 2257, Darres was promoted to the rank of commander. That same year, he was assigned by Starfleet Intelligence to the USS Farragut to investigate the incident at Tycho IV. While there, Darres befriended Lieutenant James T. Kirk, and helped convince him to remain in the service. Darres remained on the Farragut for six months.
In 2263, Darres and Casden crossed paths again, and briefly renewed their friendship.
In 2268, following the death of all hands, including Captain Casden, aboard the USS Sphinx, Darres was assigned to investigate the matter. However, Darres died in a transporter malfunction, believed by Kirk to have been purposefully caused to halt Darres' probe. Before his death, Darres had recorded and encrypted a copy of the Starfleet Charter, a clue which lead Kirk to become aware of the organization Section 31. (TOS - Section 31 novel: Cloak)