In early 2258 Jack took part in the investigation of Frank Benson's murder. Unbeknownst to Garibaldi, however, Jack gave support from inside the station to help Knight One undetectably dispose of Benson's body.
On New Year's Eve of 2258, Jack quietly assisted a man named Devereaux in setting up and shipping out some jamming equipment designed to prevent any signals from reaching Earthforce One as it approached the transfer station on Io (the plan ultimately involving the destruction of the ship and the death of President Luis Santiago). Garibaldi discovers the plot when he discovers the jamming devices. Jack shoots him in the back before he could warn anyone, taking his link and leaving him for dead. Garibaldi does not die, however, and is rushed to Medlab. After hours of surgeries, his situation becomes stuck at critical but stable. Commander Sinclair orders Jack to keep a guard posted over the Chief at all times and also order him to find Devereaux and his two companions. Jack murders all three men, making it look as though he fired on them in self-defense.
Jack would bide his time for over three weeks while Garibaldi was in a coma. When he woke up, at first, he could not remember who shot him, relieving Jack who stood nearby. However, soon thereafter Talia Winters scanned Garibaldi to uncover the truth. Jack was arrested by Lou Welch and other members of security. Garibaldi interrogated him personally, though Jack couldn't help but gloat about being on the "winning" side of a "new order" about to take over on Earth. He gave Garibaldi a strange salute and said "Be seeing you" at the close of the interrogation (the same farewell Psi Cop Bester gave Sinclair the previous year.) President Morgan Clark personally ordered Jack sent back to Earth, ostensibly for a deeper investigation. However, en route, Jack was transferred to another ship and disappeared.