From Halopedia, the Halo wiki
Dimitri was stationed on the ship when it sacrificed its slipspace drive in 2531 and entered into cryostasis along with the rest of the crew and complement. In 2559, he and the others were awakened to find themselves above the Banished-controlled Installation 00. During the battle to retake the Ark, Dimitri's team was traveling through woods enroute to a storage facility a few klicks from their position. After a long march, the team had become relaxed by their surroundings and dropped their guard. Suddenly a lone cloaked Sangheili struck at the group and impaled Dimitri with its energy sword, killing him. Dimitri's comrade, Floyd, alerted the rest of their squad and they proceeded to fire several rounds at the spot where Dimitri had been standing. However, the Elite had already retreated into the woods. Not wanting to get picked off while going after the cloaked Elite, the marines tossed their grenades into the nearby trees. A moment later, the team pushed through the burning trees and found no sign of the Sangheili. Private D. Wood collected Dimitri's dog tags and noted in journal that they would never again forget they were in a battlefield.
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