Changeling Hunter - Cults who hunt shapechangers

[aeauseth]

I'm working on a side mission for a player who is a changeling (http://www.dandwiki.com/wiki/Changelings_(3.5e_Race)). My basic concept is to create a religious offshoot of a standard religion (specific religion undetermined, but Lawful Good). These zealots believe that demons and devils plan to infiltrate the prime material plane by assuming human form. They hunt all who use illusions, alter self, polymorph, and of course shapechangers. They prefer to take their quarry alive so they can be questioned to locate additional targets, and possibly gain proof that furthers their belief of the impending invasion. They think those hiding amongst us are vying for positions of power and trying to determine our weaknesses. They value truth and honesty. They are reluctant to harm any humanoid born of the material plane, although mistakenly believe that all shapechangers are outsiders.

I'm currently considering using Church Inquisitor (http://dndtools.eu/classes/church-inquisitor/) as the bulk of their followers. Their Pierce Illusion and Force Shapechange seem to fit their purpose exceptionally well. I might tweak the PrC to be more Paladin-ish.

My side mission is likely to include a contingent of these zealots that try to capture (or kill) the changeling. Not quite an assassination, but in that general vein. I'd like to make them a re-occurring theme, so I need a decent background for this religious sect.

So does such an organization already exist in the DnD pantheon? Any suggestions on which religion they might splintered from?