Colonel Stone is the aptly named stone-faced commander of the Haegum's security department. He is a tall man, lean and hungry, with alert eyes and impassive face, the very image of what an experienced Guard officer should look like. To those that interact with him he seems a bit odd, not uncivil or threatening (unless you've earned his ire that is), but just subtly wrong.

Stone is a untouchable, one of the very rare mutants that seem immune to psychic powers. In Stone's case his untouchable aura is largely confined to his own mind; he is not one of those untouchables that can null out psychic powers within a large area. Yet even a low-key untouchable like Stone feels subtly wrong to normal people (and even more so to psykers).

The Colonel, like several of his senior security staff, all hail from the same planet (although which planet, and thus by extension which unit/founding, is apparently highly classified). Within the Haegum it is known that their unit was somehow involved in a major anti-heretical campaign that left all the survivors mentally scarred. Those few who survived were deemed too dangerous to live, and were all scheduled for execution. Tancred, however, offered them a second option – rather than receive the Emperor's Mercy, they would submit to a mind-wipe and enter Tancred's service. Those that accepted had their minds scrubbed clean and then partially restored using electrografts, returning to them – or in many cases enhancing – their martial skills, but leaving them without memories or personalities. The process worked very well indeed thanks to the expertise of Master Kush and the medicae personnel, Sand in particular, and it has been reused several time to create more security troopers from mind-wiped subjects.

Security personnel is used primarily to guard the Haegum and external safe-houses, but also represent a pool of combat-trained manpower that can be called upon if there is need of additional fire support; the are the equivalent of veteran Inquisitorial Stormtroopers.