The Inquisitor Corp was one of 2 corps created by Tom after the fall.
The Inquisitor Corps was essentialy a stripped down version of the Social Workers. They were created to weedle information out of prisonors and to basicly fill the gaps the Social Workers couldn't.
After The end of the purge, Tom disbanded both the corps.
They were both re-instated however, a the time of the Rise Of The Blue Remnant, but both were extremly undermanned.
They have often been refered to as the Corps brothers, the inquisitor corps to find someone guilty, the executioner corps to kill someone guilty.