 The remaining traces of the taint of servility gradually faded, and the "fiefs for service" turned into proper hereditable fiefs, partly also because impoverished free nobles, while reserving their personal free status, voluntarily became "ministeriales".By the 13th century Bavarian law held that the "ministeriales" (or "Dienstmänner") held a position higher than the ordinary "milites", and only the monarchy and princes were permitted to maintain "ministeriales".Imperial courts increasingly rendered justice for ministerials, as when Count Frederick of Isenberg murdered Archbishop Engelbert of Cologne in 1225.