From Halopedia, the Halo wiki
Mission aboard Mona Lisa
Maller, though normally part of another squad along with Ayad, was assigned to Sergeant Zhao Heng Lopez's Marine detachment during a mission to investigate the prisoner transport Mona Lisa amongst the debris field of Installation 04. Unbeknownst to the Marines, the mission had been commissioned by the Office of Naval Intelligence whose operative John Smith had been experimenting on the Flood aboard the ship.
After a brief firefight with several unarmored Covenant Sangheili in the Mona Lisa's cargo bay, Maller was assigned to guard the squad's Pelican dropship and clean the cargo bay of bodies, accompanied by Cranker, Simmons and Sydney, while the others went to search for Rabbit. Not long after, Maller and his team were suddenly attacked by Pod infectors and infected, becoming part of the Flood collective.
Maller, now a Flood combat form, would later return to the Pelican, accompanied by a combat form that had been Cranker. The unsuspecting pilot, Burgundy, opened the rear ramp, only to be immediately attacked by the two Flood forms. They then proceeded to heft Burgundy to the proto-Gravemind the Flood was forming in the Mona Lisa's engine room in order to accumulate a sufficient amount of knowledge to escape the system and spread.
Along with a number of other Marines, Maller is not present in the motion comic adaptation of The Mona Lisa. Concept art of him was created during the development of the short, which can be seen below.
List of appearances