If that hexenbiest who came into the shop was Adalind's mother, and she told your mom there was a royal here in Portland, then he must have been the one she made the purification process for.
店に来た魔獣の アデリンの母親が ニックの母に ポートランドに王族が居ると話してます そして浄化薬を 彼女に精製させたのが警部です