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Mission aboard Mona Lisa
During the Red Horse's classified mission in Installation 04's debris field in the Soell system, they came across a lifepod with a single, mortally wounded survivors they dubbed "John Doe". After he had succumbed to his wounds, Tsardikos performed the autopsy. He was subsequently assigned to Sergeant Zhao Heng Lopez's squad when it was sent to investigate the prisoner transport Mona Lisa. Unbeknownst to the Marines, the mission had been commissioned by the Office of Naval Intelligence whose operative John Smith had been secretly researching the Flood on the Mona Lisa.
Upon boarding the Mona Lisa using a Pelican, the Marines were immediately attacked by a group of unarmored Sangheili in a cargo bay. After the Marines received their new orders to clear the Mona Lisa's NAV databases, Tsardikos was assigned to Corpsman Ngoc Benti's team, with the mission of purging the backup database in the engine room. They headed to the ship's recycling plant, where they were attacked by a group of Flood forms. As they were being pursued by the Flood, Tsardikos froze completely, simply staring at the Flood without even firing, though Benti managed to snap him out of it and he resumed firing. However, Tsardikos fell behind the others soon after, and was subsequently torn apart by the Flood.
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