He was a good friend of Brother Murus, and had mourned his death for some time after the latter's burial. Murus asked Garrett to bury Martello's body in the cloister graveyard. If dropped into his grave before Renault, his thankful voice is heard telling Garrett of the secret room in the winter tunnels.
He probably died before the Cataclysm began. A grave was made, but his body somehow wound up in the Cathedral attic.