Bump this from me. What I tried - first run, I decided to listen to his arguments, went to Kolsc then, listened there, returned back, slaughtered Raedric. Nothing happend afterwards (at this time both, the Priest and the Soul-Woman were alive)
Then I tried to kill the Soul-Woman and directly kill Raedric. Then I proceeded and killed everybody on this floor (where Raedric is), still nothing happened. I would really like to finish this quest as Kolsc's partner.