Alethius was an Imperial soldier. His corpse can be found inside the Nchuand-Zel Excavation Site, just before the entrance to Nchuand-Zel. He wears a full set of Imperial Armor. It is likely he has been killed by Nimhe, a giant Frostbite Spider found in the same room. He carries a note that starts the quest "The Lost Expedition."
Alethius was protecting four researchers that went out on an expedition in the excavation site, Staubin, Stromm, Erj and Krag. He was suspecting the intentions of Erj and Krag. It is revealed in Erj's Notes that Alethius's suspicions were correct, as they were planning to sell the Dwemer artifacts recovered.
- If his body is moved from its location near the entrance of Nchuand-Zel, it will move back to its initial spot after a few days.
- His note is written to someone named Salonia. Only two characters with that name exist in Skyrim, however, neither of them appear to have any connection to him.