Originally Posted by Dumma
Do you mean those boxes you get from the Poirot NPC for killing the semi-boss monsters or do you get a completion box another way?
Yes, those boxes. You get one box for fighting the boss going up the tower the first way (talk to Poirot after the boss on the safe floor to get it), then another by doing the Reinvestigation quest.
Reinvestigation from my findings can only be done once a day per character per boss.