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Following the Covenant ambush of Arbiter Thel 'Vadam in the Elder Council Chamber during the Battle of Nuusra, Mahlo investigated as part of his duties as security officer for the Swords of Sanghelios. Interrogating a captured Covenant Grunt, Mahlo learned that Murok 'Vadam had betrayed them and promptly informed Thel. Perhaps believing that Thel would not execute a member of his own clan, Murok confessed that the Covenant had promised him power and prestige in exchange for Thel's location, unaware that in their severely weakened state, the Covenant couldn't fulfill that promise. Enraged, Thel executed Murok for his treason.
Mahlo documented the event on his data pad which was later accessed by members of the Fireteam Osiris while they were in the Swords of Sanghelios camp following the conclusion of the Battle of Nuusra.
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