Board Thread:Warhammer 40k Roleplay/@comment-28917471-20150603055254/@comment-25177957-20150606100412

Ok, Supahbadmarine, we've had this exact same arguement before in that Hive World RP, let me quote a segement concenring Inquisitorial Storm Troopers from the page on this wiki.

"''Inquisitorial Storm Troopers - The Inquisition maintains a number of fortresses throughout the galaxy, both secret and known to the inhabitants of the Imperium. Inquisitorial Storm Troopers are used by the Imperial Inquisition to guard their fortresses and the Black Ships as they make their purity runs across the Imperium's sectors, as well as to augment an individual Inquisitor's personal forces with reliable and effective soldiers. Many Storm Troopers of particular skill are chosen to become an Inquisitor's Throne Agents. Inquisitorial Storm Troopers are selected from families with a record of unwavering faith in the Emperor and prior duty to the Inquisition. They are trained and equipped in a manner similar to standard Imperial Guard Storm Troopers, albeit lacking the rapid insertion and infiltration skills, as they are not expected to undertake such types of missions. Such activities are more often carried out for the Inquisition by the Officio Assassinorum. "''

So to rephrase, that paragraph states that an Inquisitorial Storm Trooper might also serve as a personal Throne Agent. Not once was it stated that the IST Kreisner met was still a member of the Imperial Guard when he met Kreisner, he was a Throne Agent. Let that sink in, a member of an Inquisitor's personal retinue.

You can find more information this type of Storm Trooper in the Dark Heresy rulebook, and in the Witch Hunters codex.