"Some may be able to avoid the Judges of the Adeptus Arbites, fewer may be able to face off against the Imperial Guard and the Adeptus Astartes, but let it be known that none can stand against the Officio Assassinorum."
The Ordo Sicarius is one of the Ordos Minoris of the Inquisition, and is assigned to monitor and control the Officio Assassinorum. The Ordo was created by Inquisitor Jaegar after his investigation into the Wars of Vindication which resulted in the apparent death of the Grand Master of Assassins. Like the Ordo Hereticus, this organisation was born out of the chaotic events of the Age of Apostasy in the 36th Millennium. After a vicious and secret internecine conflict within the Assassin Temples, the Temples were devastated, and Inquisitorial investigation into the contradictory actions of the Officio Assassinorum during the second great Imperial civil war led to the decision that the Assassin Temples required dedicated monitoring. Given the terrifying capacity of the various Officio Assassinorum operatives it was deemed necessary that an Inquisitorial organization should oversee the running of the temples and ensure their actions were in keeping with wider Imperial policy. It is the members of the Ordo Sicarius who dispatch Officio operatives on their missions, either in response to a specific request by the High Lords of Terra or another Inquisitor, or for objectives they themselves deem important. Given the obscure nature of this Ordo's duties, they are little known outside the halls of high Imperial power, and even then, they are a subtle player in the great game of Imperial politics.
Tziz Jarek was an infamous rogue Callidus Assassin who was active during the Wars of Vindication, which took place shortly after the death of the Renegade High Lord Goge Vandire during the Age of Apostasy's Reign of Blood in the early 36th Millennium. Vandire had managed to corrupt many within the Officio Assassinorum, just as he had bribed and blackmailed his way through the other Imperial Adepta. Foremost amongst Vandire's agents was Tziz Jarek. Using the shapeshifting drug Polymorphine, Jarek had assassinated the Grand Master of the Officio Assassinorum and assumed his identity. However, unbeknownst to Jarek, the Grand Master had expected such a plot and had a decoy Assassin take his place in his chambers. As such, Jarek had not killed the true Grand Master, who secretly mustered those still loyal to him and the Emperor to fight against this usurper.
A heinous battle raged within the Imperial Palace itself amongst the various factions of Assassins as they brought their terrible skills to war. Ancient arsenals of the Officio Assassinorum were unleashed and terrifying weaponry, long since banned by the Senatorum Imperialis, were brought to bear by the Assassins on both sides against one another. In the end, the true Grand Master assassinated Jarek and disappeared into a self-imposed exile. The Officio’s hierarchy was shattered and needed to be rebuilt from the ground up. After the conclusion of the Wars of Vindication, following a thorough investigation, Inquisitor Jaeger deemed that a special order of the Inquisition was needed to monitor and to control the Officio Assassinorum much more closely. His proposal was accepted, and the hidden order of the Inquisition known as the Ordo Sicarius was created to monitor the Officio Assassinorum for signs of corruption and to police their activities to prevent such an event from occurring again.
As the Officio Assassinorum is a highly secretive branch of the Imperial hierarchy, the only way to properly monitor its operatives was to plant Assassin-Acolytes and Inquisitors within their ranks. Acolytes of the Ordo Sicarius often find themselves placed within the trusted circles of many high-ranking members of the Imperium or on loan to Inquisitors of other Ordos where their skill set would be extremely useful. As an added precaution, the various Assassin Temples' operations were split up and scattered to separate locations throughout the galaxy to ensure that if one should fall to xenos influence, daemonancy or heresy, another would remain untainted. Further rules were also put into place to ensure that no single individual could abuse wielding the immense power of the Officio Assassinorum to serve their own ambitions.
The Ordo Sicarius is responsible for investigating and controlling the Officio Assassinorum. By ancient decree, no Imperial Assassin may be deployed without the consent of the High Lords of Terra. This is, of course, highly impractical and quite often an Inquisitor of the Ordo Sicarius will sanction the Officio Assassinorum under the guise of an edict from Terra. While some believe this to be an abuse of their power, in a galaxy-spanning civilisation, such measures are essential to maintain a level of response to the myriad threats faced by Mankind.
The Ordo Sicarius is also responsible for overseeing the Culexus Temple of the Officio Assassinorum, whose operatives are unique psychic Blanks. Between the Ordo Sicarius and the operatives of the Culexus Temple, an Inquisitor has a much greater chance of encountering, and perhaps even studying, an Untouchable, as the number of individuals born with the anti-psychic Pariah Gene is vanishingly small in the human population. However, a member of the Ordo Sicarius is able to gain access to such individuals every few years and study them at length.
- Codex: Assassins (2nd Edition), pp. 5-7
- Dark Heresy: Daemon Hunter (RPG), pp. 54-55
- Inquisitor: The Thorians (Specialty Game Sourcebook) by Gav Thorpe, pg. 20