The Serpens Assassin is the moniker used to refer to the individual responsible for killing the Betrayer of Humanity, Emperor of House Cygnus and the Empire. They are known to be of House Serpens; Nobuo of the Qa'a family.
In 3198 they killed the Cygnus Emperor by as yet unknown methods.
In 3199 they turned themselves over to the custody of The High Church of Messiah-as-Emperox, where they were held within The Chamber of The Mirrored Eye whilst the High Church discussed the consequences of the Assassin's actions.
During Miansha 3200, the High Church determined that the Soul of the Assassin should be judged by God and God alone. The Execution of the Assassin took place on Election Day 3200.