Ciello was one of the soldiers fighting the Chinese invaders when they first attacked Anchorage, Alaska. At the time, he was with his friend Henry Hodges. One of Henry Hodges' Holodisks explains how Ciello died. Ciello was being handed some ammunition from Henry Hodges when a shell hit and exploded, killing Ciello.
It is unknown whether Ciello actually existed in the Fallout universe and whether he is "real" since his only mention is inside the Anchorage Reclamation simulation which is not completely accurate historically.